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Sparks S, Hayes G, Pinto J, Bulte D. Characterising cerebrovascular reactivity and the pupillary light response-a comparative study. Front Physiol 2024; 15:1384113. [PMID: 39175613 PMCID: PMC11338921 DOI: 10.3389/fphys.2024.1384113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Accepted: 07/29/2024] [Indexed: 08/24/2024] Open
Abstract
Introduction Smooth muscle is integral to multiple autonomic systems, including cerebrovascular dynamics through vascular smooth muscle cells and in ocular muscle dynamics, by regulating pupil size. In the brain, smooth muscle function plays a role in cerebrovascular reactivity (CVR) that describes changes in blood vessel calibre in response to vasoactive stimuli. Similarly, pupil size regulation can be measured using the pupillary light response (PLR), the pupil's reaction to changes in light levels. The primary aim of this study was to explore the interplay between cerebral blood flow and pupil dynamics, evaluated using CVR and PLR, respectively. Methods A total of 20 healthy adults took part in a CVR gas stimulus protocol and a light and dark flash PLR protocol. CVR was calculated as the blood flow velocity change in the middle cerebral artery, measured using transcranial Doppler ultrasound in response to a 5% increase in CO2. Multiple PLR metrics were evaluated with a clinical pupillometer. Results CVR and PLR metrics were all within the expected physiological ranges for healthy adults. Nine different PLR metrics, assessed through the light and dark flash protocols, were compared against CVR. A significant negative relationship was observed between the latency of the PLR in the dark flash protocol and CVR. No statistically significant relationships were found between CVR and other PLR metrics. Conclusion This is the first study to investigate the relationship between cerebral blood flow and pupil dynamics. A significant relationship between dark flash latency and CVR was observed. Future work includes evaluating these relationships using more robust CVR and PLR measurement techniques in a larger, more diverse cohort. Notably, more research is warranted into the PLR using a dark flash protocol and its connection to cerebrovascular function.
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Affiliation(s)
| | | | | | - Daniel Bulte
- Institute of Biomedical Engineering, Department of Engineering Science, University of Oxford, Oxford, United Kingdom
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Turner R, Rasmussen P, Gatterer H, Tremblay JC, Roche J, Strapazzon G, Roveri G, Lawley J, Siebenmann C. Cerebral blood flow regulation in hypobaric hypoxia: role of haemoconcentration. J Physiol 2024. [PMID: 38687185 DOI: 10.1113/jp285169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Accepted: 04/04/2024] [Indexed: 05/02/2024] Open
Abstract
During acute hypoxic exposure, cerebral blood flow (CBF) increases to compensate for the reduced arterial oxygen content (CaO2). Nevertheless, as exposure extends, both CaO2 and CBF progressively normalize. Haemoconcentration is the primary mechanism underlying the CaO2 restoration and may therefore explain, at least in part, the CBF normalization. Accordingly, we tested the hypothesis that reversing the haemoconcentration associated with extended hypoxic exposure returns CBF towards the values observed in acute hypoxia. Twenty-three healthy lowlanders (12 females) completed two identical 4-day sojourns in a hypobaric chamber, one in normoxia (NX) and one in hypobaric hypoxia (HH, 3500 m). CBF was measured by ultrasound after 1, 6, 12, 48 and 96 h and compared between sojourns to assess the time course of changes in CBF. In addition, CBF was measured at the end of the HH sojourn after hypervolaemic haemodilution. Compared with NX, CBF was increased in HH after 1 h (P = 0.001) but similar at all later time points (all P > 0.199). Haemoglobin concentration was higher in HH than NX from 12 h to 96 h (all P < 0.001). While haemodilution reduced haemoglobin concentration from 14.8 ± 1.0 to 13.9 ± 1.2 g·dl-1 (P < 0.001), it did not increase CBF (974 ± 282 to 872 ± 200 ml·min-1; P = 0.135). We thus conclude that, at least at this moderate altitude, haemoconcentration is not the primary mechanism underlying CBF normalization with acclimatization. These data ostensibly reflect the fact that CBF regulation at high altitude is a complex process that integrates physiological variables beyond CaO2. KEY POINTS: Acute hypoxia causes an increase in cerebral blood flow (CBF). However, as exposure extends, CBF progressively normalizes. We investigated whether hypoxia-induced haemoconcentration contributes to the normalization of CBF during extended hypoxia. Following 4 days of hypobaric hypoxic exposure (corresponding to 3500 m altitude), we measured CBF before and after abolishing hypoxia-induced haemoconcentration by hypervolaemic haemodilution. Contrary to our hypothesis, the haemodilution did not increase CBF in hypoxia. Our findings do not support haemoconcentration as a stimulus for the CBF normalization during extended hypoxia.
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Affiliation(s)
- Rachel Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
- Institut für Sportwissenschaft, Universität Innsbruck, Tyrol, Austria
| | | | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Joshua C Tremblay
- School of Sport and Health Sciences, Cardiff Metropolitan University, Wales, UK
| | - Johanna Roche
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giulia Roveri
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Justin Lawley
- Institut für Sportwissenschaft, Universität Innsbruck, Tyrol, Austria
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Sprick JD, Sabino‐Carvalho J, Mekonnen E, McGranahan M, Zanuzzi M, DaCosta D, Park J. Cerebrovascular carbon dioxide reactivity is intact in chronic kidney disease. Physiol Rep 2024; 12:e15998. [PMID: 38570312 PMCID: PMC10990926 DOI: 10.14814/phy2.15998] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 03/14/2024] [Accepted: 03/22/2024] [Indexed: 04/05/2024] Open
Abstract
Chronic kidney disease (CKD) is characterized by an elevated risk for cerebrovascular disease including stroke. One mechanism that may contribute to this heightened risk is an impairment in cerebrovascular carbon dioxide reactivity (CVR). We compared CVR between CKD patients stages III-IV and controls (CON) without CKD but matched for hypertension and diabetes status. CVR was measured via 5% CO2 inhalation followed by voluntary hyperventilation in 14 CKD and 11 CON participants while mean arterial pressure, end-tidal carbon dioxide, and middle cerebral artery blood velocity (MCAv) were measured continuously. CVR was quantified as the linear relationship between etCO2 and MCAv. We observed no difference in CVR between groups. Hypercapnic CVR: CKD = 1.2 ± 0.9 cm/s/mm Hg, CON = 1.3 ± 0.8 cm/s/mm Hg, hypocapnic CVR: CKD = 1.3 ± 0.9 cm/s/mm Hg, CON = 1.5 ± 0.7 cm/s/mm Hg, integrated CVR: CKD = 1.5 ± 1.1 cm/s/mm Hg, CON = 1.7 ± 0.8 cm/s/mm Hg, p ≥ 0.48. Unexpectedly, CVR was inversely related to estimated glomerular filtration rate in CKD (R2 = 0.37, p = 0.02). We report that CVR remains intact in CKD and is inversely related to eGFR. These findings suggest that other mechanisms beyond CVR contribute to the elevated stroke risk observed in CKD.
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Affiliation(s)
- Justin D. Sprick
- Department of Kinesiology, Health Promotion and RecreationUniversity of North TexasDentonTexasUSA
| | - Jeann Sabino‐Carvalho
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Elsa Mekonnen
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Melissa McGranahan
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Matias Zanuzzi
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Dana DaCosta
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
| | - Jeanie Park
- Division of Renal Medicine, Department of MedicineEmory University School of MedicineAtlantaGeorgiaUSA
- Research Service Line, Atlanta VA Health Care SystemDecaturGeorgiaUSA
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Hoogeveen ES, Pelzer N, Ghariq E, van Osch MJP, Dahan A, Terwindt GM, Kruit MC. Cerebrovascular reactivity to hypercapnia in patients with migraine: A dual-echo arterial spin labeling MRI study. Headache 2024; 64:276-284. [PMID: 38429974 DOI: 10.1111/head.14680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 12/14/2023] [Accepted: 12/20/2023] [Indexed: 03/03/2024]
Abstract
OBJECTIVE This study aimed to compare cerebrovascular reactivity between patients with migraine and controls using state-of-the-art magnetic resonance imaging (MRI) techniques. BACKGROUND Migraine is associated with an increased risk of cerebrovascular disease, but the underlying mechanisms are still not fully understood. Impaired cerebrovascular reactivity has been proposed as a link. Previous studies have evaluated cerebrovascular reactivity with different methodologies and results are conflicting. METHODS In this single-center, observational, case-control study, we included 31 interictal patients with migraine without aura (aged 19-66 years, 17 females) and 31 controls (aged 22-64 years, 18 females) with no history of vascular disease. Global and regional cerebrovascular reactivities were assessed with a dual-echo arterial spin labeling (ASL) 3.0 T MRI scan of the brain which measured the change in cerebral blood flow (CBF) and BOLD (blood oxygen level dependent) signal to inhalation of 5% carbon dioxide. RESULTS When comparing patients with migraine to controls, cerebrovascular reactivity values were similar between the groups, including mean gray matter CBF-based cerebrovascular reactivity (3.2 ± 0.9 vs 3.4 ± 1% ΔCBF/mmHg CO2 ; p = 0.527), mean gray matter BOLD-based cerebrovascular reactivity (0.18 ± 0.04 vs 0.18 ± 0.04% ΔBOLD/mmHg CO2 ; p = 0.587), and mean white matter BOLD-based cerebrovascular reactivity (0.08 ± 0.03 vs 0.08 ± 0.02% ΔBOLD/mmHg CO2 ; p = 0.621).There was no association of cerebrovascular reactivity with monthly migraine days or migraine disease duration (all analyses p > 0.05). CONCLUSION Cerebrovascular reactivity to carbon dioxide seems to be preserved in patients with migraine without aura.
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Affiliation(s)
- E S Hoogeveen
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - N Pelzer
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - E Ghariq
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
- Department of Radiology and Nuclear Medicine, Medisch Spectrum Twente, Enschede, The Netherlands
| | - M J P van Osch
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
- C.J. Gorter MRI Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
| | - A Dahan
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| | - G M Terwindt
- Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands
| | - M C Kruit
- Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands
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Chen DY, Di X, Yu X, Biswal BB. The significance and limited influence of cerebrovascular reactivity on age and sex effects in task- and resting-state brain activity. Cereb Cortex 2024; 34:bhad448. [PMID: 38212284 PMCID: PMC10832986 DOI: 10.1093/cercor/bhad448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2023] [Accepted: 10/31/2023] [Indexed: 01/13/2024] Open
Abstract
Functional MRI measures the blood-oxygen-level dependent signals, which provide an indirect measure of neural activity mediated by neurovascular responses. Cerebrovascular reactivity affects both task-induced and resting-state blood-oxygen-level dependent activity and may confound inter-individual effects, such as those related to aging and biological sex. We examined a large dataset containing breath-holding, checkerboard, and resting-state tasks. We used the breath-holding task to measure cerebrovascular reactivity, used the checkerboard task to obtain task-based activations, and quantified resting-state activity with amplitude of low-frequency fluctuations and regional homogeneity. We hypothesized that cerebrovascular reactivity would be correlated with blood-oxygen-level dependent measures and that accounting for these correlations would result in better estimates of age and sex effects. We found that cerebrovascular reactivity was correlated with checkerboard task activations in the visual cortex and with amplitude of low-frequency fluctuations and regional homogeneity in widespread fronto-parietal regions, as well as regions with large vessels. We also found significant age and sex effects in cerebrovascular reactivity, some of which overlapped with those observed in amplitude of low-frequency fluctuations and regional homogeneity. However, correcting for the effects of cerebrovascular reactivity had very limited influence on the estimates of age and sex. Our results highlight the limitations of accounting for cerebrovascular reactivity with the current breath-holding task.
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Affiliation(s)
- Donna Y Chen
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, United States
- Rutgers Biomedical and Health Sciences, Rutgers School of Graduate Studies, Newark, NJ 08901, United States
| | - Xin Di
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, United States
| | - Xin Yu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, MA 02114, United States
| | - Bharat B Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ 07102, United States
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Carr JMJR, Day TA, Ainslie PN, Hoiland RL. The jugular venous-to-arterial P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference during rebreathing and end-tidal forcing: Relationship with cerebral perfusion. J Physiol 2023; 601:4251-4262. [PMID: 37635691 DOI: 10.1113/jp284449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 08/11/2023] [Indexed: 08/29/2023] Open
Abstract
We examined two assumptions of the modified rebreathing technique for the assessment of the ventilatory central chemoreflex (CCR) and cerebrovascular CO2 reactivity (CVR), hypothesizing: (1) that rebreathing abolishes the gradient between the partial pressures of arterial and brain tissue CO2 [measured via the surrogate jugular venousP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ and arterialP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference (Pjv-a CO2 )] and (2) rebreathing eliminates the capacity of CVR to influence the Pjv-a CO2 difference, and thus affect CCR sensitivity. We also evaluated these variables during two separate dynamic end-tidal forcing (ETF) protocols (termed: ETF-1 and ETF-2), another method of assessing CCR sensitivity and CVR. Healthy participants were included in the rebreathing (n = 9), ETF-1 (n = 11) and ETF-2 (n = 10) protocols and underwent radial artery and internal jugular vein (advanced to jugular bulb) catheterization to collect blood samples. Transcranial Doppler ultrasound was used to measure middle cerebral artery blood velocity (MCAv). The Pjv-a CO2 difference was not abolished during rebreathing (6.2 ± 2.6 mmHg; P < 0.001), ETF-1 (9.3 ± 1.5 mmHg; P < 0.001) or ETF-2 (8.6 ± 1.4 mmHg; P < 0.001). The Pjv-a CO2 difference did not change during the rebreathing protocol (-0.1 ± 1.2 mmHg; P = 0.83), but was reduced during the ETF-1 (-3.9 ± 1.1 mmHg; P < 0.001) and ETF-2 (-3.4 ± 1.2 mmHg; P = 0.001) protocols. Overall, increases in MCAv were associated with reductions in the Pjv-a CO2 difference during ETF (-0.095 ± 0.089 mmHg cm-1 s-1 ; P = 0.001) but not during rebreathing (-0.028 ± 0.045 mmHg · cm-1 · s-1 ; P = 0.067). These findings suggest that, although the Pjv-a CO2 is not abolished during any chemoreflex assessment technique, hyperoxic hypercapnic rebreathing is probably more appropriate to assess CCR sensitivity independent of cerebrovascular reactivity to CO2 . KEY POINTS: Modified rebreathing is a technique used to assess the ventilatory central chemoreflex and is based on the premise that the rebreathing method eliminates the difference between arterial and brain tissueP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Therefore, rebreathing is assumed to isolate the ventilatory response to central chemoreflex stimulation from the influence of cerebral blood flow. We assessed these assumptions by measuring arterial and jugular venous bulbP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ and middle cerebral artery blood velocity during modified rebreathing and compared these data against data from another test of the ventilatory central chemoreflex using hypercapnic dynamic end-tidal forcing. The difference between arterial and jugular venous bulbP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ remained present during both rebreathing and end-tidal forcing tests, whereas middle cerebral artery blood velocity was associated with theP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ difference during end-tidal forcing but not rebreathing. These findings offer substantiating evidence that clarifies and refines the assumptions of modified rebreathing tests, enhancing interpretation of future findings.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Centre for Heart, Lung and Vascular Health, University of British Columbia Okanagan, Kelowna, BC, Canada
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
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Chen DY, Di X, Yu X, Biswal BB. The Significance and Limited Influence of Cerebrovascular Reactivity on Age and Sex Effects in Task- and Resting-State Brain Activity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.18.553848. [PMID: 37662201 PMCID: PMC10473673 DOI: 10.1101/2023.08.18.553848] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Functional MRI (fMRI) measures the blood-oxygen-level dependent (BOLD) signals, which provide an indirect measure of neural activity mediated by neurovascular responses. Cerebrovascular reactivity affects both task-induced and resting-state BOLD activity and may confound inter-individual effects observed in BOLD-based measures, such as those related to aging and biological sex. To investigate this, we examined a large open-access fMRI dataset containing a breath-holding task, checkerboard task, and resting-state scans. We used the breath-holding task to measure cerebrovascular reactivity, used the checkerboard task to obtain task-based activations, and from the resting-state data, we quantified the resting-state amplitude of low-frequency fluctuations (ALFF), and resting-state regional homogeneity (ReHo). We hypothesized that cerebrovascular reactivity would be correlated with BOLD measures and that accounting for these correlations would result in better estimates of age and sex effects. Our analysis showed that cerebrovascular reactivity was correlated with checkerboard task activations in the visual cortex and with ALFF and ReHo in widespread fronto-parietal regions, as well as regions with large vessels. We also found significant age and sex effects in cerebrovascular reactivity, some of which overlapped with those observed in ALFF and ReHo scores. Finally, we demonstrated that correcting for the effects of cerebrovascular reactivity had very limited influence on the estimates of age and sex. Our results highlight the limitations of accounting for cerebrovascular reactivity with the current breath-holding task.
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Affiliation(s)
- Donna Y. Chen
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
- Rutgers Biomedical and Health Sciences, Rutgers School of Graduate Studies, Newark, NJ, USA
| | - Xin Di
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
| | - Xin Yu
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Harvard Medical School, Massachusetts General Hospital, Charlestown, Massachusetts, USA
| | - Bharat B. Biswal
- Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA
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Skinner BD, Weaver SRC, Lucas SJE, Lucas RAI. Menstrual phase influences cerebrovascular responsiveness in females but may not affect sex differences. Front Physiol 2023; 13:1035452. [PMID: 36685202 PMCID: PMC9846518 DOI: 10.3389/fphys.2022.1035452] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Background and aims: Sex differences in the rate and occurrence of cerebrovascular diseases (e.g., stroke) indicate a role for female sex hormones (i.e., oestrogen and progesterone) in cerebrovascular function and regulation. However, it remains unclear how cerebrovascular function differs between the sexes, and between distinct phases of the menstrual cycle. This study aimed to compare cerebrovascular-CO2 responsiveness in 1) females during the early follicular (EF), ovulatory (O) and mid-luteal (ML) phases of their menstrual cycle; and 2) males compared to females during phases of lower oestrogen (EF) and higher oestrogen (O). Methods: Eleven females (25 ± 5 years) complete experimental sessions in the EF (n = 11), O (n = 9) and ML (n = 11) phases of the menstrual cycle. Nine males (22 ± 3 years) completed two experimental sessions, approximately 2 weeks apart for comparison to females. Middle and posterior cerebral artery velocity (MCAv, PCAv) was measured at rest, during two stages of hypercapnia (2% and 5% CO2 inhalation) and hypocapnia (voluntary hyperventilation to an end-tidal CO2 of 30 and 24 mmHg). The linear slope of the cerebral blood velocity response to changes in end-tidal CO2 was calculated to measure cerebrovascular-CO2 responsiveness.. Results: In females, MCAv-CO2 responsiveness to hypocapnia was lower during EF (-.78 ± .45 cm/s/mmHg) when compared to the O phase (-1.17 ± .52 cm/s/mmHg; p < .05) and the ML phase (-1.30 ± .82; p < .05). MCAv-CO2 responsiveness to hypercapnia and hypo-to-hypercapnia, and PCAv-CO2 responsiveness across the CO2 range were similar between menstrual phases (p ≥ .20). MCAv-CO2 responsiveness to hypo-to hypercapnia was greater in females compared to males (3.12 ± .91 cm/s/mmHg vs. 2.31 ± .46 cm/s/mmHg; p = .03), irrespective of menstrual phase (EF or O). Conclusion: Females during O and ML phases have an enhanced vasoconstrictive capacity of the MCA compared to the EF phase. Additionally, biological sex differences can influence cerebrovascular-CO2 responsiveness, dependent on the insonated vessel.
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Affiliation(s)
- Bethany D. Skinner
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom,Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom,*Correspondence: Bethany D. Skinner,
| | - Samuel R. C. Weaver
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom,Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Samuel J. E. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom,Centre for Human Brain Health, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Rebekah A. I. Lucas
- School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
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The Influence of Carbon Dioxide on Cerebral Autoregulation During Sevoflurane-based Anesthesia in Patients With Type 2 Diabetes. J Neurosurg Anesthesiol 2023; 35:65-73. [PMID: 34387283 DOI: 10.1097/ana.0000000000000794] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/06/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND Cerebral autoregulation (CA) continuously adjusts cerebrovascular resistance to maintain cerebral blood flow (CBF) constant despite changes in blood pressure. Also, CBF is proportional to changes in arterial carbon dioxide (CO 2 ) (cerebrovascular CO 2 reactivity). Hypercapnia elicits cerebral vasodilation that attenuates CA efficacy, while hypocapnia produces cerebral vasoconstriction that enhances CA efficacy. In this study, we quantified the influence of sevoflurane anesthesia on CO 2 reactivity and the CA-CO 2 relationship. METHODS We studied patients with type 2 diabetes mellitus (DM), prone to cerebrovascular disease, and compared them to control subjects. In 33 patients (19 DM, 14 control), end-tidal CO 2 , blood pressure, and CBF velocity were monitored awake and during sevoflurane-based anesthesia. CA, calculated with transfer function analysis assessing phase lead (degrees) between low-frequency oscillations in CBF velocity and mean arterial blood pressure, was quantified during hypocapnia, normocapnia, and hypercapnia. RESULTS In both control and DM patients, awake CO 2 reactivity was smaller (2.8%/mm Hg CO 2 ) than during sevoflurane anesthesia (3.9%/mm Hg; P <0.005). Hyperventilation increased CA efficacy more (3 deg./mm Hg CO 2 ) in controls than in DM patients (1.8 deg./mm Hg CO 2 ; P <0.001) in both awake and sevoflurane-anesthetized states. CONCLUSIONS The CA-CO 2 relationship is impaired in awake patients with type 2 DM. Sevoflurane-based anesthesia does not further impair this relationship. In patients with DM, hypocapnia induces cerebral vasoconstriction, but CA efficacy does not improve as observed in healthy subjects.
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Glodzik L, Rusinek H, Butler T, Li Y, Storey P, Sweeney E, Osorio RS, Biskaduros A, Tanzi E, Harvey P, Woldstad C, Maloney T, de Leon MJ. Higher body mass index is associated with worse hippocampal vasoreactivity to carbon dioxide. Front Aging Neurosci 2022; 14:948470. [PMID: 36158536 PMCID: PMC9491849 DOI: 10.3389/fnagi.2022.948470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Accepted: 07/22/2022] [Indexed: 11/24/2022] Open
Abstract
Background and objectives Obesity is a risk factor for cognitive decline. Probable mechanisms involve inflammation and cerebrovascular dysfunction, leading to diminished cerebral blood flow (CBF) and cerebrovascular reactivity (CVR). The hippocampus, crucially involved in memory processing and thus relevant to many types of dementia, poses a challenge in studies of perfusion and CVR, due to its location, small size, and complex shape. We examined the relationships between body mass index (BMI) and hippocampal resting CBF and CVR to carbon dioxide (CVRCO2) in a group of cognitively normal middle-aged and older adults. Methods Our study was a retrospective analysis of prospectively collected data. Subjects were enrolled for studies assessing the role of hippocampal hemodynamics as a biomarker for AD among cognitively healthy elderly individuals (age > 50). Participants without cognitive impairment, stroke, and active substance abuse were recruited between January 2008 and November 2017 at the NYU Grossman School of Medicine, former Center for Brain Health. All subjects underwent medical, psychiatric, and neurological assessments, blood tests, and MRI examinations. To estimate CVR, we increased their carbon dioxide levels using a rebreathing protocol. Relationships between BMI and brain measures were tested using linear regression. Results Our group (n = 331) consisted of 60.4% women (age 68.8 ± 7.5 years; education 16.8 ± 2.2 years) and 39.6% men (age 70.4 ± 6.4 years; education 16.9 ± 2.4 years). Approximately 22% of them (n = 73) were obese. BMI was inversely associated with CVRCO2 (β = -0.12, unstandardized B = -0.06, 95% CI -0.11, -0.004). A similar relationship was observed after excluding subjects with diabetes and insulin resistance (β = -0.15, unstandardized B = -0.08, 95% CI -0.16, -0.000). In the entire group, BMI was more strongly related to hippocampal CVRCO2 in women (β = -0.20, unstandardized B = -0.08, 95% CI -0.13, -0.02). Discussion These findings lend support to the notion that obesity is a risk factor for hippocampal hemodynamic impairment and suggest targeting obesity as an important prevention strategy. Prospective studies assessing the effects of weight loss on brain hemodynamic measures and inflammation are warranted.
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Affiliation(s)
- Lidia Glodzik
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Henry Rusinek
- Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States
| | - Tracy Butler
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Yi Li
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Pippa Storey
- Department of Radiology, New York University Grossman School of Medicine, New York, NY, United States
| | - Elizabeth Sweeney
- Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA, United States
| | - Ricardo S. Osorio
- Department of Psychiatry, New York University Grossman School of Medicine, New York, NY, United States
| | - Adrienne Biskaduros
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Emily Tanzi
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Patrick Harvey
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Christopher Woldstad
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Thomas Maloney
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
| | - Mony J. de Leon
- Department of Radiology, Brain Health Imaging Institute, Weill Cornell Medicine, New York, NY, United States
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11
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Scholkmann F, Tachtsidis I, Wolf M, Wolf U. Systemic physiology augmented functional near-infrared spectroscopy: a powerful approach to study the embodied human brain. NEUROPHOTONICS 2022; 9:030801. [PMID: 35832785 PMCID: PMC9272976 DOI: 10.1117/1.nph.9.3.030801] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 06/07/2022] [Indexed: 05/15/2023]
Abstract
In this Outlook paper, we explain why an accurate physiological interpretation of functional near-infrared spectroscopy (fNIRS) neuroimaging signals is facilitated when systemic physiological activity (e.g., cardiorespiratory and autonomic activity) is measured simultaneously by employing systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS). The rationale for SPA-fNIRS is twofold: (i) SPA-fNIRS enables a more complete interpretation and understanding of the fNIRS signals measured at the head since they contain components originating from neurovascular coupling and from systemic physiological sources. The systemic physiology signals measured with SPA-fNIRS can be used for regressing out physiological confounding components in fNIRS signals. Misinterpretations can thus be minimized. (ii) SPA-fNIRS enables to study the embodied brain by linking the brain with the physiological state of the entire body, allowing novel insights into their complex interplay. We envisage the SPA-fNIRS approach will become increasingly important in the future.
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Affiliation(s)
- Felix Scholkmann
- University of Bern, Institute of Complementary and Integrative Medicine, Bern, Switzerland
- University Hospital Zurich, University of Zurich, Biomedical Optics Research Laboratory, Neonatology Research, Department of Neonatology, Zurich, Switzerland
| | - Ilias Tachtsidis
- University College London, Biomedical Optics Research Laboratory, Department of Medical Physics and Biomedical Engineering, London, United Kingdom
| | - Martin Wolf
- University Hospital Zurich, University of Zurich, Biomedical Optics Research Laboratory, Neonatology Research, Department of Neonatology, Zurich, Switzerland
| | - Ursula Wolf
- University of Bern, Institute of Complementary and Integrative Medicine, Bern, Switzerland
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12
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Sayegh ALC, Fan JL, Vianna LC, Dawes M, Paton JFR, Fisher JP. Sex-differences in the sympathetic neurocirculatory responses to chemoreflex activation. J Physiol 2022; 600:2669-2689. [PMID: 35482235 PMCID: PMC9324851 DOI: 10.1113/jp282327] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 04/25/2022] [Indexed: 11/08/2022] Open
Abstract
Abstract The purpose of this study was to determine whether there are sex differences in the cardiorespiratory and sympathetic neurocirculatory responses to central, peripheral, and combined central and peripheral chemoreflex activation. Ten women (29 ± 6 years, 22.8 ± 2.4 kg/m2: mean ± SD) and 10 men (30 ± 7 years, 24.8 ± 3.2 kg/m2) undertook randomized 5 min breathing trials of: room air (eucapnia), isocapnic hypoxia (10% oxygen (O2); peripheral chemoreflex activation), hypercapnic hyperoxia (7% carbon dioxide (CO2), 50% O2; central chemoreflex activation) and hypercapnic hypoxia (7% CO2, 10% O2; central and peripheral chemoreflex activation). Control trials of isocapnic hyperoxia (peripheral chemoreflex inhibition) and hypocapnic hyperoxia (central and peripheral chemoreflex inhibition) were also included. Muscle sympathetic nerve activity (MSNA; microneurography), mean arterial pressure (MAP; finger photoplethysmography) and minute ventilation (V˙E; pneumotachometer) were measured. Total MSNA (P = 1.000 and P = 0.616), MAP (P = 0.265) and V˙E (P = 0.587 and P = 0.472) were not different in men and women during eucapnia and during isocapnic hypoxia. Women exhibited attenuated increases in V˙E during hypercapnic hyperoxia (27.3 ± 6.3 vs. 39.5 ± 7.5 l/min, P < 0.0001) and hypercapnic hypoxia (40.9 ± 9.1 vs. 53.8 ± 13.3 l/min, P < 0.0001) compared with men. However, total MSNA responses were augmented in women (hypercapnic hyperoxia 378 ± 215 vs. 258 ± 107%, P = 0.017; hypercapnic hypoxia 607 ± 290 vs. 362 ± 268%, P < 0.0001). No sex differences in total MSNA, MAP or V˙E were observed during isocapnic hyperoxia and hypocapnic hyperoxia. Our results indicate that young women have augmented sympathetic responses to central chemoreflex activation, which explains the augmented MSNA response to combined central and peripheral chemoreflex activation. Key points Sex differences in the control of breathing have been well studied, but whether there are differences in the sympathetic neurocirculatory responses to chemoreflex activation between healthy women and men is incompletely understood. We observed that, compared with young men, young women displayed augmented increases in muscle sympathetic nerve activity during both hypercapnic hyperoxia (central chemoreflex activation) and hypercapnic hypoxia (central and peripheral chemoreflex activation) but had attenuated increases in minute ventilation. In contrast, no sex differences were found in either muscle sympathetic nerve activity or minute ventilation responses to isocapnic hypoxia (peripheral chemoreceptor stimulation). Young women have blunted ventilator, but augmented sympathetic responses, to central (hypercapnic hyperoxia) and combined central and peripheral chemoreflex activation (hypercapnic hypoxia), compared with young men. The possible causative association between the reduced ventilation and heightened sympathetic responses in young women awaits validation.
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Affiliation(s)
- Ana Luiza C Sayegh
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Jui-Lin Fan
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Lauro C Vianna
- NeuroV̇ASQ̇ - Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Brasília, DF, Brazil
| | - Mathew Dawes
- Department of Medicine, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - Julian F R Paton
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
| | - James P Fisher
- Manaaki Manawa - The Centre for Heart Research, Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland, New Zealand
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13
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Madsen TE, Samaei M, Pikula A, Yu AYX, Carcel C, Millsaps E, Yalamanchili RS, Bencie N, Dula AN, Leppert M, Rundek T, Dreyer RP, Bushnell C. Sex Differences in Physical Activity and Incident Stroke: A Systematic Review. Clin Ther 2022; 44:586-611. [PMID: 35418311 PMCID: PMC9195871 DOI: 10.1016/j.clinthera.2022.02.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 02/03/2022] [Accepted: 02/12/2022] [Indexed: 12/25/2022]
Abstract
PURPOSE Physical inactivity, a modifiable risk factor for cardiovascular disease, is independently associated with stroke. Though some prior data have suggested sex differences in levels of physical activity, whether there are sex differences in the role of physical activity in primary stroke prevention is largely unknown. This systematic review identifies and describes recent findings on sex differences in the association between physical activity and incident (first-ever) stroke. This review also describes the current evidence on the strength of the association between physical activity and a reduced stroke risk in women in particular. METHODS Using a prespecified strategy, PubMed/MEDLINE and Cochrane Central were searched to identify observational studies or trials published from 2000 to 2020 and reporting sex differences in physical activity and incident stroke. To be included, among other criteria, studies had to include sex-specific effect estimates from women, men, or both. Titles, abstracts, and full-text articles were screened to identify studies meeting the inclusion criteria, and adjusted sex-specific estimates of the association between physical activity and incident stroke for total stroke (ischemic plus hemorrhagic) or ischemic stroke were abstracted. FINDINGS Thirty-seven studies met the inclusion criteria. Of 17 studies that included data on total incident stroke (ischemic and hemorrhagic combined) in both women and men, 7 (41%) showed similar associations between physical activity and incident stroke between women and men, 6 (35%) suggested a significant effect in women but not in men, and 3 (18%) showed a significant effect in men but not in women. Of 10 studies that included data on ischemic stroke in women and men, 5 (50%) suggested similar effects in women and men, 4 (40%) suggested a significant effect in women but not in men, and 1 (10%) showed an effect in men but not women. In women specifically, the majority of included studies demonstrated a reduced risk for incident stroke with physical activity, with relative risk reductions ranging from 11% to 72%, though most estimates fell between 20% and 40%. IMPLICATIONS The majority of studies indicated a clear association between physical activity and a reduction in stroke risk. Studies were split as to the potential for sex differences in this association. Future prospective investigations should identify strategies for the use of increased physical activity for primary stroke prevention, with sex-specific considerations as warranted. The data on sex-specific dose-response relationship between physical activity and stroke risk are inconclusive and warrant more research.
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Affiliation(s)
- Tracy E Madsen
- Department of Emergency Medicine, Warren Alpert Medical School, and the Department of Epidemiology, School of Public Health, Brown University, Providence, Rhode Island.
| | - Mehrnoosh Samaei
- Department of Emergency Medicine, Division of Sex and Gender in Emergency Medicine, Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Aleksandra Pikula
- Department of Medicine (Neurology), University of Toronto, University Health Networks, Toronto, Ontario, Canada
| | - Amy Y X Yu
- Department of Medicine (Neurology), University of Toronto, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
| | - Cheryl Carcel
- The George Institute for Global Health, University of New South Wales, Sydney, New South Wales, Australia
| | | | | | - Nicole Bencie
- Warren Alpert Medical School, Brown University, Providence, Rhode Island
| | - Adrienne N Dula
- Departments of Neurology and Diagnostic Medicine, Dell Medical School, University of Texas, Austin, Texas
| | - Michelle Leppert
- Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado
| | - Tatjana Rundek
- Department of Neurology, Miller School of Medicine, University of Miami, Miami, Florida
| | - Rachel P Dreyer
- Center for Outcomes Research and Evaluation, Department of Emergency Medicine, Yale School of Medicine, New Haven, Connecticut
| | - Cheryl Bushnell
- Department of Neurology, Wake Forest School of Medicine, Winston-Salem, North Carolina
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14
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Caldwell HG, Hoiland RL, Smith KJ, Brassard P, Bain AR, Tymko MM, Howe CA, Carr JMJR, Stacey BS, Bailey DM, Drapeau A, Sekhon MS, MacLeod DB, Ainslie PN. Trans-cerebral HCO 3- and PCO 2 exchange during acute respiratory acidosis and exercise-induced metabolic acidosis in humans. J Cereb Blood Flow Metab 2022; 42:559-571. [PMID: 34904461 PMCID: PMC8943603 DOI: 10.1177/0271678x211065924] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/03/2021] [Accepted: 11/11/2021] [Indexed: 01/06/2023]
Abstract
This study investigated trans-cerebral internal jugular venous-arterial bicarbonate ([HCO3-]) and carbon dioxide tension (PCO2) exchange utilizing two separate interventions to induce acidosis: 1) acute respiratory acidosis via elevations in arterial PCO2 (PaCO2) (n = 39); and 2) metabolic acidosis via incremental cycling exercise to exhaustion (n = 24). During respiratory acidosis, arterial [HCO3-] increased by 0.15 ± 0.05 mmol ⋅ l-1 per mmHg elevation in PaCO2 across a wide physiological range (35 to 60 mmHg PaCO2; P < 0.001). The narrowing of the venous-arterial [HCO3-] and PCO2 differences with respiratory acidosis were both related to the hypercapnia-induced elevations in cerebral blood flow (CBF) (both P < 0.001; subset n = 27); thus, trans-cerebral [HCO3-] exchange (CBF × venous-arterial [HCO3-] difference) was reduced indicating a shift from net release toward net uptake of [HCO3-] (P = 0.004). Arterial [HCO3-] was reduced by -0.48 ± 0.15 mmol ⋅ l-1 per nmol ⋅ l-1 increase in arterial [H+] with exercise-induced acidosis (P < 0.001). There was no relationship between the venous-arterial [HCO3-] difference and arterial [H+] with exercise-induced acidosis or CBF; therefore, trans-cerebral [HCO3-] exchange was unaltered throughout exercise when indexed against arterial [H+] or pH (P = 0.933 and P = 0.896, respectively). These results indicate that increases and decreases in systemic [HCO3-] - during acute respiratory/exercise-induced metabolic acidosis, respectively - differentially affect cerebrovascular acid-base balance (via trans-cerebral [HCO3-] exchange).
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Affiliation(s)
- Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Ryan L Hoiland
- Department of Anesthesiology, Pharmacology and Therapeutics, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, BC, Canada
| | - Kurt J Smith
- Department of Exercise Science, Physical and Health Education, Faculty of Education, University of Victoria, Victoria, British Columbia, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Anthony R Bain
- Faculty of Human Kinetics, Department of Kinesiology, University of Windsor, Windsor, ON, Canada
| | - Michael M Tymko
- Neurovascular Health Laboratory, Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Connor A Howe
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Jay MJR Carr
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
| | - Benjamin S Stacey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Damian M Bailey
- Neurovascular Research Laboratory, Faculty of Life Sciences and Education, University of South Wales, Pontypridd, UK
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Québec, Canada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, QC, Canada
| | - Mypinder S Sekhon
- Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, Vancouver General Hospital, University of British Columbia, Vancouver, BC, Canada
| | - David B MacLeod
- Human Pharmacology and Physiology Lab, Department of Anesthesiology, Duke University Medical Center, Durham, NC, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, BC, Canada
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15
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Whitaker AA, Aaron SE, Kaufman CS, Kurtz BK, Bai SX, Vidoni ED, Montgomery RN, Billinger SA. Cerebrovascular response to an acute bout of low-volume high-intensity interval exercise and recovery in young healthy adults. J Appl Physiol (1985) 2022; 132:236-246. [PMID: 34882027 PMCID: PMC8759972 DOI: 10.1152/japplphysiol.00484.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
High-intensity interval exercise (HIIT) is performed widely. However, there is a gap in knowledge regarding the acute cerebrovascular response to low-volume HIIT. Our objective was to characterize the middle cerebral artery blood velocity (MCAv) response during an acute bout of low-volume HIIT in young healthy adults. We hypothesized that MCAv would decrease below the baseline (BL), 1) during HIIT, 2) immediately following HIIT, and 3) 30 min after HIIT. As a secondary objective, we investigated sex differences in the MCAv response during HIIT. Twenty-four young healthy adults completed HIIT [12 males, age = 25 (SD = 2)]. HIIT included 10 min of 1-min high intensity (∼70% estimated maximal Watts) and active recovery (10% estimated maximal Watts) intervals on a recumbent stepper. MCAv, mean arterial pressure (MAP), heart rate (HR), and end-tidal carbon dioxide ([Formula: see text]) were recorded at BL, during HIIT, immediately following HIIT, and 30 min after HIIT. Contrary to our hypothesis, MCAv remained above BL during HIIT. MCAv peaked at minute 3 then decreased concomitantly with [Formula: see text]. MCAv was lower than BL immediately following HIIT (P < 0.001). Thirty minutes after HIIT, MCAv returned to BL (P = 0.47). Compared with men, women had a higher MCAv at BL (P = 0.001), during HIIT (P = 0.009), immediately following HIIT (P = 0.004), and 30 min after HIIT (P = 0.001). MCAv did not decrease below BL during low-volume HIIT. However, MCAv decreased below BL immediately following HIIT and returned to resting values 30 min after HIIT. MCAv also differed between sexes.NEW & NOTEWORTHY We are the first, to our knowledge, to characterize the cerebrovascular and hemodynamic response to low-volume high-intensity interval exercise (HIIT, 1-min intervals) in young healthy adults. Middle cerebral artery blood velocity (MCAv) decreased during the HIIT bout and rebounded during active recovery. Women demonstrated a significantly higher resting MCAv than men and the difference remained during HIIT. Here, we report a novel protocol and characterized the MCAv response during an acute bout of low-volume HIIT.
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Affiliation(s)
- Alicen A. Whitaker
- 1Department of Physical Therapy, Rehabilitation Science, and Athletic Training, University of Kansas Medical Center, Kansas City, Kansas
| | - Stacey E. Aaron
- 1Department of Physical Therapy, Rehabilitation Science, and Athletic Training, University of Kansas Medical Center, Kansas City, Kansas
| | - Carolyn S. Kaufman
- 2Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas
| | - Brady K. Kurtz
- 1Department of Physical Therapy, Rehabilitation Science, and Athletic Training, University of Kansas Medical Center, Kansas City, Kansas
| | - Stephen X. Bai
- 3Department of Physical Medicine and Rehabilitation, University of Kansas Medical Center, Kansas City, Kansas
| | - Eric D. Vidoni
- 4University of Kansas Alzheimer’s Disease Research
Center, Fairway, Kansas
| | - Robert N. Montgomery
- 5Department of Biostatistics & Data Science, University of Kansas Medical Center, Kansas City, Kansas
| | - Sandra A. Billinger
- 1Department of Physical Therapy, Rehabilitation Science, and Athletic Training, University of Kansas Medical Center, Kansas City, Kansas,2Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas,3Department of Physical Medicine and Rehabilitation, University of Kansas Medical Center, Kansas City, Kansas,4University of Kansas Alzheimer’s Disease Research
Center, Fairway, Kansas,6Department of Neurology, University of Kansas Medical Center, Kansas City, Kansas
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16
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Churchill NW, Hutchison MG, Graham SJ, Schweizer TA. Sex differences in acute and long-term brain recovery after concussion. Hum Brain Mapp 2021; 42:5814-5826. [PMID: 34643005 PMCID: PMC8596946 DOI: 10.1002/hbm.25591] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 05/14/2021] [Accepted: 07/01/2021] [Indexed: 12/25/2022] Open
Abstract
Concussion is associated with acute disturbances in brain function and behavior, with potential long‐term effects on brain health. However, it is presently unclear whether there are sex differences in acute and long‐term brain recovery. In this study, magnetic resonance imaging (MRI) was used to scan 61 participants with sport‐related concussion (30 male, 31 female) longitudinally at acute injury, medical clearance to return to play (RTP), and 1‐year post‐RTP. A large cohort of 167 controls (80 male, 87 female) was also imaged. Each MRI session assessed cerebral blood flow (CBF), along with white matter fractional anisotropy (FA) and mean diffusivity (MD). For concussed athletes, the parameters were converted to difference scores relative to matched control subgroups, and partial least squares modeled the main and sex‐specific effects of concussion. Although male and female athletes did not differ in acute symptoms or time to RTP , all MRI measures showed significant sex differences during recovery. Males had greater reductions in occipital‐parietal CBF (mean difference and 95%CI: 9.97 ml/100 g/min, [4.84, 15.12] ml/100 g/min, z = 3.73) and increases in callosal MD (9.07 × 10−5, [−14.14, −3.60] × 10−5, z = −3.46), with greatest effects at 1‐year post‐RTP. In contrast, females had greater reductions in FA of the corona radiata (16.50 × 10−3, [−22.38, −11.08] × 10−3, z = −5.60), with greatest effects at RTP. These findings provide new insights into how the brain recovers after a concussion, showing sex differences in both the acute and chronic phases of injury.
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Affiliation(s)
- Nathan W Churchill
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada.,Neuroscience Research Program, St. Michael's Hospital, Toronto, ON, Canada
| | - Michael G Hutchison
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada.,Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Simon J Graham
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.,Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, Canada
| | - Tom A Schweizer
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada.,Neuroscience Research Program, St. Michael's Hospital, Toronto, ON, Canada.,Faculty of Medicine (Neurosurgery), University of Toronto, Toronto, ON, Canada.,The Institute of Biomaterials and Biomedical Engineering (IBBME) at the University of Toronto, Toronto, ON, Canada
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17
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Klinzing S, Stretti F, Pagnamenta A, Bèchir M, Brandi G. Transcranial color-coded duplex sonography assessment of cerebrovascular reactivity to carbon dioxide: an interventional study. BMC Neurol 2021; 21:305. [PMID: 34364365 PMCID: PMC8349098 DOI: 10.1186/s12883-021-02310-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/06/2021] [Indexed: 01/15/2023] Open
Abstract
Background The investigation of CO2 reactivity (CO2-CVR) is used in the setting of, e.g., traumatic brain injury (TBI). Transcranial color-coded duplex sonography (TCCD) is a promising bedside tool for monitoring cerebral hemodynamics. This study used TCCD to investigate CO2-CVR in volunteers, in sedated and mechanically ventilated patients without TBI and in sedated and mechanically ventilated patients in the acute phase after TBI. Methods This interventional investigation was performed between March 2013 and February 2016 at the surgical ICU of the University Hospital of Zurich. Ten volunteers (group 1), ten sedated and mechanically ventilated patients (group 2), and ten patients in the acute phase (12–36 h) after severe TBI (group 3) were included. CO2-CVR to moderate hyperventilation (∆ CO2 -5.5 mmHg) was assessed by TCCD. Results CO2-CVR was 2.14 (1.20–2.70) %/mmHg in group 1, 2.03 (0.15–3.98) %/mmHg in group 2, and 3.32 (1.18–4.48)%/mmHg in group 3, without significant differences among groups. Conclusion Our data did not yield evidence for altered CO2-CVR in the early phase after TBI examined by TCCD. Trial registration Part of this trial was performed as preparation for the interventional trial in TBI patients (clinicaltrials.gov NCT03822026, 30.01.2019, retrospectively registered).
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Affiliation(s)
- Stephanie Klinzing
- Institute for Intensive Medicine, University Hospital of Zurich, Raemistrasse 100, CH-8091, Zurich, Switzerland.
| | - Federica Stretti
- Intensive Care Unit, Westmead Hospital, Westmead, NSW, Australia
| | - Alberto Pagnamenta
- Intensive Care Unit, Regional Hospital of Mendrisio, Mendrisio, Switzerland.,Unit of Clinical Epidemiology, Ente Ospedaliero Cantonale, Bellinzona, Switzerland.,Division of Pneumology, University of Geneva, Geneva, Switzerland
| | - Markus Bèchir
- Institute for Intensive Medicine, University Hospital of Zurich, Raemistrasse 100, CH-8091, Zurich, Switzerland
| | - Giovanna Brandi
- Institute for Intensive Medicine, University Hospital of Zurich, Raemistrasse 100, CH-8091, Zurich, Switzerland
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18
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Stringer MS, Blair GW, Shi Y, Hamilton I, Dickie DA, Doubal FN, Marshall IM, Thrippleton MJ, Wardlaw JM. A Comparison of CVR Magnitude and Delay Assessed at 1.5 and 3T in Patients With Cerebral Small Vessel Disease. Front Physiol 2021; 12:644837. [PMID: 34149442 PMCID: PMC8207286 DOI: 10.3389/fphys.2021.644837] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 04/15/2021] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Cerebrovascular reactivity (CVR) measures blood flow change in response to a vasoactive stimulus. Impairment is associated with several neurological conditions and can be measured using blood oxygen level-dependent (BOLD) magnetic resonance imaging (MRI). Field strength affects the BOLD signal, but the effect on CVR is unquantified in patient populations. METHODS We recruited patients with minor ischemic stroke and assessed CVR magnitude and delay time at 3 and 1.5 Tesla using BOLD MRI during a hypercapnic challenge. We assessed subcortical gray (GM) and white matter (WM) differences using Wilcoxon signed rank tests and scatterplots. Additionally, we explored associations with demographic factors, WM hyperintensity burden, and small vessel disease score. RESULTS Eighteen of twenty patients provided usable data. At 3T vs. 1.5T: mean CVR magnitude showed less variance (WM 3T: 0.062 ± 0.018%/mmHg, range 0.035, 0.093; 1.5T: 0.057 ± 0.024%/mmHg, range 0.016, 0.094) but was not systematically higher (Wilcoxon signal rank tests, WM: r = -0.33, confidence interval (CI): -0.013, 0.003, p = 0.167); delay showed similar variance (WM 3T: 40 ± 12 s, range: 12, 56; 1.5T: 31 ± 13 s, range 6, 50) and was shorter in GM (r = 0.33, CI: -2, 9, p = 0.164) and longer in WM (r = -0.59, CI: -16, -2, p = 0.010). Patients with higher disease severity tended to have lower CVR at 1.5 and 3T. CONCLUSION Mean CVR magnitude at 3T was similar to 1.5T but showed less variance. GM/WM delay differences may be affected by low signal-to-noise ratio among other factors. Although 3T may reduce variance in CVR magnitude, CVR is readily assessable at 1.5T and reveals comparable associations and trends with disease severity.
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Affiliation(s)
- Michael S. Stringer
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - Gordon W. Blair
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - Yulu Shi
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- Beijing Tiantan Hospital Affiliated to Capital Medical University, Beijing, China
| | - Iona Hamilton
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - David A. Dickie
- College of Medical, Veterinary, and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Fergus N. Doubal
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - Ian M. Marshall
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - Michael J. Thrippleton
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
| | - Joanna M. Wardlaw
- Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, United Kingdom
- UK Dementia Research Institute at the University of Edinburgh, Edinburgh, United Kingdom
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19
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Smith EC, Pizzey FK, Askew CD, Mielke GI, Ainslie PN, Coombes JS, Bailey TG. Effects of cardiorespiratory fitness and exercise training on cerebrovascular blood flow and reactivity: a systematic review with meta-analyses. Am J Physiol Heart Circ Physiol 2021; 321:H59-H76. [PMID: 34018848 DOI: 10.1152/ajpheart.00880.2020] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
We address two aims: Aim 1 (Fitness Review) compares the effect of higher cardiorespiratory fitness (CRF) (e.g., endurance athletes) with lower CRF (e.g., sedentary adults) on cerebrovascular outcomes, including middle cerebral artery velocity (MCAv), cerebrovascular reactivity and resistance, and global cerebral blood flow, as assessed by transcranial Doppler (TCD) or magnetic resonance imaging (MRI). Aim 2 (Exercise Training Review) determines the effect of exercise training on cerebrovascular outcomes. Systematic review of studies with meta-analyses where appropriate. Certainty of evidence was assessed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE). Twenty studies (18 using TCD) met the eligibility criteria for Aim 1, and 14 studies (8 by TCD) were included for Aim 2. There was a significant effect of higher CRF compared with lower CRF on cerebrovascular resistance (effect size = -0.54, 95% confidence interval = -0.91 to -0.16) and cerebrovascular reactivity (0.98, 0.41-1.55). Studies including males only demonstrated a greater effect of higher CRF on cerebrovascular resistance than mixed or female studies (male only: -0.69, -1.06 to -0.32; mixed and female studies: 0.10, -0.28 to 0.49). Exercise training did not increase MCAv (0.05, -0.21 to 0.31) but showed a small nonsignificant improvement in cerebrovascular reactivity (0.60, -0.08 to 1.28; P = 0.09). Exercise training showed heterogeneous effects on regional but little effect on global cerebral blood flow as measured by MRI. High CRF positively effects cerebrovascular function, including decreased cerebrovascular resistance and increased cerebrovascular reactivity; however, global cerebral blood flow and MCAv are primarily unchanged following an exercise intervention in healthy and clinical populations.NEW & NOTEWORTHY Higher cardiorespiratory fitness is associated with lower cerebrovascular resistance and elevated cerebrovascular reactivity at rest. Only adults with a true-high fitness based on normative data exhibited elevated middle cerebral artery velocity. The positive effect of higher compared with lower cardiorespiratory fitness on resting cerebrovascular resistance was more evident in male-only studies when compared with mixed or female-only studies. A period of exercise training resulted in negligible changes in middle cerebral artery velocity and global cerebral blood flow, with potential for improvements in cerebrovascular reactivity.
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Affiliation(s)
- Emily C Smith
- Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Faith K Pizzey
- Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Christopher D Askew
- VasoActive Research Group, School of Health and Sport Sciences, University of the Sunshine Coast, Sunshine Coast, Queensland, Australia.,Sunshine Coast Health Institute, Sunshine Coast Hospital and Health Service, Birtinya, Queensland, Australia
| | - Gregore I Mielke
- Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, British Columbia, Canada
| | - Jeff S Coombes
- Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
| | - Tom G Bailey
- Physiology and Ultrasound Laboratory in Science and Exercise, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,Centre for Research on Exercise, Physical Activity and Health, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia.,School of Nursing, Midwifery and Social Work, The University of Queensland, Brisbane, Queensland, Australia
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20
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Carr JMJR, Caldwell HG, Ainslie PN. Cerebral blood flow, cerebrovascular reactivity and their influence on ventilatory sensitivity. Exp Physiol 2021; 106:1425-1448. [PMID: 33932955 DOI: 10.1113/ep089446] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 04/26/2021] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the topic of this review? Cerebrovascular reactivity to CO2 , which is a principal factor in determining ventilatory responses to CO2 through the role reactivity plays in determining cerebral extra- and intracellular pH. What advances does it highlight? Recent animal evidence suggests central chemoreceptor vasculature may demonstrate regionally heterogeneous cerebrovascular reactivity to CO2 , potentially as a protective mechanism against excessive CO2 washout from the central chemoreceptors, thereby allowing ventilation to reflect the systemic acid-base balance needs (respiratory changes in P aC O 2 ) rather than solely the cerebral needs. Ventilation per se does not influence cerebrovascular reactivity independent of changes in P aC O 2 . ABSTRACT Alveolar ventilation and cerebral blood flow are both predominantly regulated by arterial blood gases, especially arterial P C O 2 , and so are intricately entwined. In this review, the fundamental mechanisms underlying cerebrovascular reactivity and central chemoreceptor control of breathing are covered. We discuss the interaction of cerebral blood flow and its reactivity with the control of ventilation and ventilatory responsiveness to changes in P C O 2 , as well as the lack of influence of ventilation itself on cerebrovascular reactivity. We briefly summarize the effects of arterial hypoxaemia on the relationship between ventilatory and cerebrovascular response to both P C O 2 and P O 2 . We then highlight key methodological considerations regarding the interaction of reactivity and ventilatory sensitivity, including the following: regional heterogeneity of cerebrovascular reactivity; a pharmacological approach for the reduction of cerebral blood flow; reactivity assessment techniques; the influence of mean arterial blood pressure; and sex-related differences. Finally, we discuss ventilatory and cerebrovascular control in the context of high altitude and congestive heart failure. Future research directions and pertinent questions of interest are highlighted throughout.
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Affiliation(s)
- Jay M J R Carr
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Hannah G Caldwell
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, University of British Columbia - Okanagan Campus, British Columbia, Canada
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21
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Rosenberg AJ, Kay VL, Anderson GK, Luu ML, Barnes HJ, Sprick JD, Rickards CA. The impact of acute central hypovolemia on cerebral hemodynamics: does sex matter? J Appl Physiol (1985) 2021; 130:1786-1797. [PMID: 33914663 DOI: 10.1152/japplphysiol.00499.2020] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Trauma-induced hemorrhage is a leading cause of disability and death due, in part, to impaired perfusion and oxygenation of the brain. It is unknown if cerebrovascular responses to blood loss are differentiated based on sex. We hypothesized that compared to males, females would have reduced tolerance to simulated hemorrhage induced by maximal lower body negative pressure (LBNP), and this would be associated with an earlier reduction in cerebral blood flow and cerebral oxygenation. Healthy young males (n = 29, 26 ± 4 yr) and females (n = 23, 27 ± 5 yr) completed a step-wise LBNP protocol to presyncope. Mean arterial pressure (MAP), stroke volume (SV), middle cerebral artery velocity (MCAv), end-tidal CO2 (etCO2), and cerebral oxygen saturation (ScO2) were measured continuously. Unexpectedly, tolerance to LBNP was similar between the sexes (males, 1,604 ± 68 s vs. females, 1,453 ± 78 s; P = 0.15). Accordingly, decreases (%Δ) in MAP, SV, MCAv, and ScO2 were similar between males and females throughout LBNP and at presyncope (P ≥ 0.20). Interestingly, although decreases in etCO2 were similar between the sexes throughout LBNP (P = 0.16), at presyncope, the %Δ etCO2 from baseline was greater in males compared to females (-30.8 ± 2.6% vs. -21.3 ± 3.0%; P = 0.02). Contrary to our hypothesis, sex does not influence tolerance, or the central or cerebral hemodynamic responses to simulated hemorrhage. However, the etCO2 responses at presyncope do suggest potential sex differences in cerebral vascular sensitivity to CO2 during central hypovolemia.NEW & NOTEWORTHY Tolerance and cerebral blood velocity responses to simulated hemorrhage (elicited by lower body negative pressure) were similar between male and female subjects. Interestingly, the change in etCO2 from baseline was greater in males compared to females at presyncope, suggesting potential sex differences in cerebral vascular sensitivity to CO2 during simulated hemorrhage. These findings may facilitate development of individualized therapeutic interventions to improve survival from hemorrhagic injuries in both men and women.
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Affiliation(s)
- Alexander J Rosenberg
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas.,Integrative Physiology Laboratory, Department of Kinesiology and Nutrition, University of Illinois at Chicago, Illinois
| | - Victoria L Kay
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Garen K Anderson
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - My-Loan Luu
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Haley J Barnes
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
| | - Justin D Sprick
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas.,Division of Renal Medicine, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia
| | - Caroline A Rickards
- Cerebral and Cardiovascular Physiology Laboratory, Department of Physiology and Anatomy, University of North Texas Health Science Center, Fort Worth, Texas
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22
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Churchill NW, Hutchison MG, Graham SJ, Schweizer TA. Disturbances in Brain Physiology Due to Season Play: A Multi-Sport Study of Male and Female University Athletes. Front Physiol 2021; 12:653603. [PMID: 33868020 PMCID: PMC8044759 DOI: 10.3389/fphys.2021.653603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 03/01/2021] [Indexed: 11/16/2022] Open
Abstract
High-performance university athletes experience frequent exertion, resulting in disrupted biological homeostasis, but it is unclear to what extent brain physiology is affected. We examined whether athletes without overtraining symptoms show signs of increased neurophysiological stress over the course of a single athletic season, and whether the effects are modified by demographic factors of age, sex and concussion history, and sport-related factors of contact exposure and season length. Fifty-three university-level athletes were recruited from multiple sports at a single institution and followed longitudinally from beginning of season (BOS) to end of season (EOS) and 1 month afterwards, with a subset followed up at the subsequent beginning of season. MRI was used to comprehensively assess white matter (WM) diffusivity, cerebral blood flow (CBF), and brain activity, while overtraining symptoms were assessed with Hooper’s Index (HI). Although athletes did not report increased HI scores, they showed significantly increased white matter diffusivity and decreased CBF at EOS and 1 month afterwards, with recovery at follow-up. Global brain activity was not significantly altered though, highlighting the ability of the brain to adapt to exercise-related stressors. Male athletes had greater white matter diffusivity at EOS, but female athletes had greater declines in CBF at 1 month afterwards. Post-season changes in MRI measures were not related to change in HI score, age, concussion history, contact exposure, or length of athletic season. Hence, the brain shows substantial but reversible neurophysiological changes due to season play in the absence of overtraining symptoms, with effects that are sex-dependent but otherwise insensitive to demographic variations. These findings provide new insights into the effects of training and competitive play on brain health.
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Affiliation(s)
- Nathan W Churchill
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada.,Neuroscience Research Program, St. Michael's Hospital, Toronto, ON, Canada
| | - Michael G Hutchison
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada.,Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, ON, Canada
| | - Simon J Graham
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.,Physical Sciences Platform, Sunnybrook Research Institute, Sunnybrook Health Sciences Center, Toronto, ON, Canada
| | - Tom A Schweizer
- Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, ON, Canada.,Neuroscience Research Program, St. Michael's Hospital, Toronto, ON, Canada.,Faculty of Medicine (Neurosurgery), University of Toronto, Toronto, ON, Canada.,The Institute of Biomaterials & Biomedical Engineering (IBBME) at the University of Toronto, Toronto, ON, Canada
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23
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Schoech L, Allie K, Salvador P, Martinez M, Rivas E. Sex Differences in Thermal Comfort, Perception, Feeling, Stress and Focus During Exercise Hyperthermia. Percept Mot Skills 2021; 128:969-987. [PMID: 33730933 DOI: 10.1177/00315125211002096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
It is unclear whether men and women perceive thermal stress differently when changes in intestinal temperature (ΔTin) and metabolic heat production (MHprod) are matched between sexes during exercise hyperthermia. This study tested the hypothesis that females have enhanced sensitivity to comfort and perception of thermal stress during exercise hyperthermia in these conditions. We had 22 healthy active adults (11 males, 11 females; M age = 22.4 years, SD = 4.9; M height = 169 cm, SD = 7.6; M weight = 68.3 kg, SD = 13) exercise in random order, separated by at least three days at similar MHprod (M = 7.0 W/kg, SD = 1.5; p = 0.32) for 60 minutes on a cycle ergometer in cool (M = 24.00C, SD = 0.0; M = 14.4%Rh, SD = 3.6) and hot (M = 42.3°C, SD = 0.2; M = 10-60%Rh) environments with a progressive increase in humidity conditions. We measured ΔTin, and thermal stress indices for sensation (TS), comfort (TC), pleasantness (TP), and stickiness (S), feeling (FS scale), stress (visual analogue stress scale, VAS), focus (F) and felt arousal (FAS scale). We examined environmental conditions as wet bulb globe temperatures (WBGT). Males and females had similar increases in ΔTin (ME: WBGT; p < 0.0001), and both groups reported increased TS and TC and decreased TP (ME: WBGT, p ≤ 0.01). However, females reported that TS, TC, and TP, felt hotter overall, more uncomfortable, and more unpleasant, compared to males (ME: Sex; p < 0.04). Overall, females felt worse and were more stressed compared to males (ME: Sex; p ≤ 0.05). Females also reported greater internal focus as WBGT increased compared to males (I: WBGT × Sex; p < 0.003). Knowing that females perceive thermal stress during exercise hyperthermia to be hotter, more uncomfortable, more unpleasant, and more stressful compared to males can help coaches/trainers plan different exercise routines for exercisers of both sexes.
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Affiliation(s)
- Lauren Schoech
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, United States
| | - Kyleigh Allie
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, United States
| | - Paolo Salvador
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, United States
| | - Mauricio Martinez
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, United States
| | - Eric Rivas
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, United States.,KBR, Human Physiology, Performance, Protection & Operations Laboratory, NASA, Johnson Space Center, Houston, Texas, United States
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24
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Roberts DR, Collins HR, Lee JK, Taylor JA, Turner M, Zaharchuk G, Wintermark M, Antonucci MU, Mulder ER, Gerlach DA, Asemani D, McGregor HR, Seidler RD. Altered cerebral perfusion in response to chronic mild hypercapnia and head-down tilt Bed rest as an analog for Spaceflight. Neuroradiology 2021; 63:1271-1281. [PMID: 33587162 DOI: 10.1007/s00234-021-02660-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 01/26/2021] [Indexed: 01/01/2023]
Abstract
PURPOSE Following prolonged stays on the International Space Station (ISS), some astronauts exhibit visual acuity changes, ophthalmological findings, and mildly elevated intracranial pressures as part of a novel process called spaceflight-associated neuro-ocular syndrome (SANS). To determine the pathophysiology of SANS, NASA conducted a multi-investigator study in which 11 healthy participants underwent head-down tilt bed rest, mimicking microgravity-induced cephalad fluid shifts, combined with elevated ambient CO2 levels similar to those on the ISS (HDT+CO2). As part of that study, we examined the effects of HDT+CO2 on cerebral perfusion. METHODS Using arterial spin labeling, we compared cerebral perfusion before, during, and after HDT+CO2 in participants who developed SANS (n = 5) with those who did not (n = 6). RESULTS All participants demonstrated a decrease in perfusion during HDT+CO2 (mean decrease of 25.1% at HDT7 and 16.2% at HDT29); however, the timing and degree of change varied between the groups. At day 7 of HDT+CO2, the SANS group experienced a greater reduction in perfusion than the non-SANS group (p =.05, 95% CI:-0.19 to 16.11, d=.94, large effect). Conversely, by day 29 of HDT+CO2, the SANS group had significantly higher perfusion (approaching their baseline) than the non-SANS group (p = .04, 95% CI:0.33 to 13.07, d=1.01, large effect). CONCLUSION Compared with baseline and recovery, HDT+CO2 resulted in reduced cerebral perfusion which varied based on SANS status. Further studies are needed to unravel the relative role of HDT vs hypercapnia, to determine if these perfusion changes are clinically relevant, and whether perfusion changes contribute to the development of SANS during spaceflight.
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Affiliation(s)
- Donna R Roberts
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA. .,Department of Neuroscience, Medical University of South Carolina, Charleston, SC, USA.
| | - Heather R Collins
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Jessica K Lee
- German Aerospace Center (DLR, Institute of Aerospace Medicine), Cologne, Germany.,Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, USA
| | - James A Taylor
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Matthew Turner
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Greg Zaharchuk
- Department of Radiology, Division of Neuroradiology, Stanford University, Stanford, CA, USA
| | - Max Wintermark
- Department of Radiology, Division of Neuroradiology, Stanford University, Stanford, CA, USA
| | - Michael U Antonucci
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Edwin R Mulder
- German Aerospace Center (DLR, Institute of Aerospace Medicine), Cologne, Germany
| | - Darius A Gerlach
- German Aerospace Center (DLR, Institute of Aerospace Medicine), Cologne, Germany
| | - Davud Asemani
- Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston, SC, USA
| | - Heather R McGregor
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, USA
| | - Rachael D Seidler
- Department of Applied Physiology and Kinesiology, College of Health and Human Performance, University of Florida, Gainesville, FL, USA.,Norman Fixel Institute for Neurological Diseases, College of Health and Human Performance, University of Florida, Gainesville, FL, USA
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25
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Rivas E, Allie KN, Salvador PM, Schoech L, Martinez M. Sex difference in cerebral blood flow velocity during exercise hyperthermia. J Therm Biol 2020; 94:102741. [PMID: 33292982 DOI: 10.1016/j.jtherbio.2020.102741] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 09/18/2020] [Accepted: 09/21/2020] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Cerebral blood flow and thermal perception during physical exercise under hyperthermia conditions in females are poorly understood. Because sex differences exist for blood pressure control, resting middle cerebral artery velocity (MCAVmean), and pain, we tested the hypothesis that females would have greater reductions in MCAvmean and increased thermal perceptual strain during exercise hyperthermia compared to males. METHODS Twenty-two healthy active males and females completed 60 min of matched exercise metabolic heat production in a 1) control cool (24.0 ± 0.0 °C; 14.4 ± 3.4% Rh) and 2) hot (42.3 ± 0.3 °C; 28.4 ± 5.2% Rh) conditions in random order, separated by at least 3 days while MCAvmean, thermal comfort, and preference was obtained during the exercise. RESULTS Compared to 36 °C mean body temperature (Mbt), as hyperthermia increased to 39 °C Mbt, females had a greater reduction in absolute (MCAvmean), and relative change (%Δ MCAvmean) and conductance (%Δ MCAvmean conductance) in MCAVmean compared to males (Interaction: Temperature x Sex, P ≤ 0.002). During exercise in cool conditions, absolute and conductance MCAvmean was maintained from rest through exercise; however, females had greater MCAVmean compared to males (Main effect: Sex, P < 0.0008). We also found disparities in females' perceptual thermal comfort and thermal preference. These differences may be associated with a greater reduction in partial pressure of end-tidal CO2, and different cardiovascular and blood pressure control to exercise under hyperthermia. CONCLUSIONS In summary, females exercise cerebral blood flow velocity is reduced to a greater extent (25% vs 15%) and the initial reduction occurs at lower hyperthermia mean body temperatures (~38 °C vs ~39 °C) and are under greater thermal perceptual strain compared to males.
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Affiliation(s)
- Eric Rivas
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA; KBR, Human Physiology, Performance, Protection & Operations Laboratory, NASA Johnson Space Center, Houston, TX, USA.
| | - Kyleigh N Allie
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Paolo M Salvador
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA
| | - Lauren Schoech
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA
| | - Mauricio Martinez
- Exercise & Thermal Integrative Physiology Laboratory, Texas Tech University, Lubbock, TX, USA; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
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26
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Shoemaker LN, Wilson LC, Lucas SJE, Machado L, Walker RJ, Cotter JD. Indomethacin markedly blunts cerebral perfusion and reactivity, with little cognitive consequence in healthy young and older adults. J Physiol 2020; 599:1097-1113. [DOI: 10.1113/jp280118] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 11/05/2020] [Indexed: 12/11/2022] Open
Affiliation(s)
- L. N. Shoemaker
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
| | - L. C. Wilson
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - S. J. E. Lucas
- Department of Physiology University of Otago Dunedin New Zealand
- School of Sport, Exercise and Rehabilitation Sciences College of Life and Environmental Sciences University of Birmingham Birmingham UK
- Centre for Human Brain Health University of Birmingham Birmingham UK
| | - L. Machado
- Department of Psychology University of Otago Dunedin New Zealand
| | - R. J. Walker
- Department of Medicine Otago Medical School ‐ Dunedin Campus University of Otago Dunedin New Zealand
| | - J. D. Cotter
- School of Physical Education, Sport and Exercise Sciences University of Otago Dunedin New Zealand
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27
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Barnes JN, Charkoudian N. Integrative cardiovascular control in women: Regulation of blood pressure, body temperature, and cerebrovascular responsiveness. FASEB J 2020; 35:e21143. [PMID: 33151577 DOI: 10.1096/fj.202001387r] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 09/21/2020] [Accepted: 10/13/2020] [Indexed: 12/14/2022]
Abstract
Over the past several decades, it has become increasingly clear that women have distinct cardiovascular profiles compared to men. In this review, our goal is to provide an overview of the literature regarding the influences of female sex and reproductive hormones (primarily estradiol) on mechanisms of cardiovascular control relevant to regulation of blood pressure, body temperature, and cerebral blood flow. Young women tend to have lower resting blood pressure compared with men. This sex difference is reversed at menopause, when women develop higher sympathetic nerve activity and the risk of systemic hypertension increases sharply as postmenopausal women age. Vascular responses to thermal stress, including cutaneous vasodilation and vasoconstriction, are also affected by reproductive hormones in women, where estradiol appears to promote vasodilation and heat dissipation. The influence of reproductive hormones on cerebral blood flow and sex differences in the ability of the cerebral vasculature to increase its blood flow (cerebrovascular reactivity) are relatively new areas of investigation. Sex and hormonal influences on integrative blood flow regulation have further implications during challenges to physiological homeostasis, including exercise. We propose that increasing awareness of these sex-specific mechanisms is important for optimizing health care and promotion of wellness in women across the life span.
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Affiliation(s)
- Jill N Barnes
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, USA
| | - Nisha Charkoudian
- US Army Research Institute of Environmental Medicine, Natick, MA, USA
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28
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Kermorgant M, Nasr N, Czosnyka M, Arvanitis DN, Hélissen O, Senard JM, Pavy-Le Traon A. Impacts of Microgravity Analogs to Spaceflight on Cerebral Autoregulation. Front Physiol 2020; 11:778. [PMID: 32719617 PMCID: PMC7350784 DOI: 10.3389/fphys.2020.00778] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 06/15/2020] [Indexed: 12/16/2022] Open
Abstract
It is well known that exposure to microgravity in astronauts leads to a plethora physiological responses such as headward fluid shift, body unloading, and cardiovascular deconditioning. When astronauts return to Earth, some encounter problems related to orthostatic intolerance. An impaired cerebral autoregulation (CA), which could be compromised by the effects of microgravity, has been proposed as one of the mechanisms responsible for orthostatic intolerance. CA is a homeostatic mechanism that maintains cerebral blood flow for any variations in cerebral perfusion pressure by adapting the vascular tone and cerebral vessel diameter. The ground-based models of microgravity are useful tools for determining the gravitational impact of spaceflight on human body. The head-down tilt bed rest (HDTBR), where the subject remains in supine position at -6 degrees for periods ranging from few days to several weeks is the most commonly used ground-based model of microgravity for cardiovascular deconditioning. head-down bed rest (HDBR) is able to replicate cephalic fluid shift, immobilization, confinement, and inactivity. Dry immersion (DI) model is another approach where the subject remains immersed in thermoneutral water covered with an elastic waterproof fabric separating the subject from the water. Regarding DI, this analog imitates absence of any supporting structure for the body, centralization of body fluids, immobilization and hypokinesia observed during spaceflight. However, little is known about the impact of microgravity on CA. Here, we review the fundamental principles and the different mechanisms involved in CA. We also consider the different approaches in order to assess CA. Finally, we focus on the effects of short- and long-term spaceflight on CA and compare these findings with two specific analogs to microgravity: HDBR and DI.
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Affiliation(s)
- Marc Kermorgant
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Nathalie Nasr
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
- Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University Hospital, Cambridge, United Kingdom
- Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Dina N. Arvanitis
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Ophélie Hélissen
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Jean-Michel Senard
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
- Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, France
| | - Anne Pavy-Le Traon
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
- Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
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Labrecque L, Drapeau A, Rahimaly K, Imhoff S, Billaut F, Brassard P. Comparable blood velocity changes in middle and posterior cerebral arteries during and following acute high-intensity exercise in young fit women. Physiol Rep 2020; 8:e14430. [PMID: 32342622 PMCID: PMC7186567 DOI: 10.14814/phy2.14430] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 04/04/2020] [Indexed: 12/13/2022] Open
Abstract
The cerebral blood flow response to high-intensity interval training (HIIT) remains unclear. HIIT induces surges in mean arterial pressure (MAP), which could be transmitted to the brain, especially early after exercise onset. The aim of this study was to describe regional cerebral blood velocity changes during and following 30 s of high-intensity exercise. Ten women (age: 27 ± 6 years; VO2max : 48.6 ± 3.8 ml·kg·min-1 ) cycled for 30 s at the workload reached at V ˙ O2max followed by 3min of passive recovery. Middle (MCAvmean ) and posterior cerebral artery mean blood velocities (PCAvmean ; transcranial Doppler ultrasound), MAP (finger photoplethysmography), and end-tidal carbon dioxide partial pressure (PET CO2 ; gaz analyzer) were measured. MCAvmean (+19 ± 10%) and PCAvmean (+21 ± 14%) increased early after exercise onset, returning toward baseline values afterward. MAP increased throughout exercise (p < .0001). PET CO2 initially decreased by 3 ± 2 mmHg (p < .0001) before returning to baseline values at end-exercise. During recovery, MCAvmean (+43 ± 15%), PCAvmean (+42 ± 15%), and PET CO2 (+11 ± 3 mmHg; p < .0001) increased. In young fit women, cerebral blood velocity quickly increases at the onset of a 30-s exercise performed at maximal workload, before returning to baseline values through the end of the exercise. During recovery, cerebral blood velocity augments in both arteries, along with PET CO2 .
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Affiliation(s)
- Lawrence Labrecque
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec‐Université LavalQuébecQuébecCanada
| | - Audrey Drapeau
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec‐Université LavalQuébecQuébecCanada
| | - Kevan Rahimaly
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec‐Université LavalQuébecQuébecCanada
| | - Sarah Imhoff
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec‐Université LavalQuébecQuébecCanada
| | - François Billaut
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec‐Université LavalQuébecQuébecCanada
| | - Patrice Brassard
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecQuébecCanada
- Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec‐Université LavalQuébecQuébecCanada
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Favre ME, Lim V, Falvo MJ, Serrador JM. Cerebrovascular reactivity and cerebral autoregulation are improved in the supine posture compared to upright in healthy men and women. PLoS One 2020; 15:e0229049. [PMID: 32119678 PMCID: PMC7051088 DOI: 10.1371/journal.pone.0229049] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 01/28/2020] [Indexed: 12/04/2022] Open
Abstract
Cerebrovascular reactivity and cerebral autoregulation are two major mechanisms that regulate cerebral blood flow. Both mechanisms are typically assessed in either supine or seated postures, but the effects of body position and sex differences remain unclear. This study examined the effects of body posture (supine vs. seated vs. standing) on cerebrovascular reactivity during hyper and hypocapnia and on cerebral autoregulation during spontaneous and slow-paced breathing in healthy men and women using transcranial Doppler ultrasonography of the middle cerebral artery. Results indicated significantly improved cerebrovascular reactivity in the supine compared with seated and standing postures (supine = 3.45±0.67, seated = 2.72±0.53, standing = 2.91±0.62%/mmHg, P<0.0167). Similarly, cerebral autoregulatory measures showed significant improvement in the supine posture during slow-paced breathing. Transfer function measures of gain significantly decreased and phase significantly increased in the supine posture compared with seated and standing postures (gain: supine = 1.98±0.56, seated = 2.37±0.53, standing = 2.36±0.71%/mmHg; phase: supine = 59.3±21.7, seated = 39.8±12.5, standing = 36.5±9.7°; all P<0.0167). In contrast, body posture had no effect on cerebral autoregulatory measures during spontaneous breathing. Men and women had similar cerebrovascular reactivity and similar cerebral autoregulation during both spontaneous and slow-paced breathing. These data highlight the importance of making comparisons within the same body position to ensure there is not a confounding effect of posture.
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Affiliation(s)
- Michelle E. Favre
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
| | - Valerie Lim
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
| | - Michael J. Falvo
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
- Department of Physical Medicine and Rehabilitation, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
- Department of Veterans Affairs, War Related Illness and Injury Study Center, East Orange, New Jersey, United States of America
| | - Jorge M. Serrador
- Department of Pharmacology, Physiology and Neuroscience, Rutgers Biomedical and Health Sciences, Newark, New Jersey, United States of America
- Department of Cardiovascular Electronics, National University of Ireland Galway, Galway, Ireland
- * E-mail:
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31
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Marley CJ, Brugniaux JV, Davis D, Calverley TA, Owens TS, Stacey BS, Tsukamoto H, Ogoh S, Ainslie PN, Bailey DM. Long-term Exercise Confers Equivalent Neuroprotection in Females Despite Lower Cardiorespiratory Fitness. Neuroscience 2020; 427:58-63. [DOI: 10.1016/j.neuroscience.2019.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 11/22/2019] [Accepted: 12/04/2019] [Indexed: 12/16/2022]
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32
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Blanken AE, Nation DA. Does Gender Influence the Relationship Between High Blood Pressure and Dementia? Highlighting Areas for Further Investigation. J Alzheimers Dis 2020; 78:23-48. [PMID: 32955459 PMCID: PMC8011824 DOI: 10.3233/jad-200245] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND Gender differences have been noted in studies linking blood pressure to all-cause dementia, and the two most common forms of dementia: Alzheimer's disease (AD) and vascular dementia (VaD). However, how gender modifies the relationship between blood pressure and dementia remains unclear. OBJECTIVE To review evidence for a gender modifying effect on the link between blood pressure and all-cause dementia. METHODS A systematic review was conducted according to PRISMA guidelines. Sixteen out of 256 reviewed articles met inclusion criteria. RESULTS For women, higher midlife systolic blood pressure (SBP) and hypertension were both associated with greater risk of all-cause dementia, AD, and VaD, in six out of seven studies. Two of these studies reported higher midlife SBP/hypertension were associated with greater risk for all-cause dementia in women, but not men. One study reported higher midlife SBP associated with greater AD risk in women, but not men. However, another study reported that midlife hypertension associated with AD risk in men, but not women. No clear gender differences were reported in the relationship between late-life high blood pressure/hypertension with all-cause dementia or AD. CONCLUSION Studies rarely, and inconsistently, analyzed or reported gender effects. Therefore, interpretation of available evidence regarding the role of gender in blood pressure associated dementia was difficult. Several studies indicated higher midlife SBP was associated with greater risk of all-cause dementia for women, compared to men. Future studies should evaluate women-specific aging processes that occur in midlife when considering the association between blood pressure and dementia risk.
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Affiliation(s)
- Anna E. Blanken
- Department of Psychology, University of Southern California, Los Angeles, CA, USA
| | - Daniel A. Nation
- Department of Psychological Science, University of California Irvine, Irvine, CA, USA
- Institute for Memory Disorders and Neurological Impairments, University of California Irvine, Irvine, CA, USA
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Miller KB, Howery AJ, Rivera-Rivera LA, Johnson SC, Rowley HA, Wieben O, Barnes JN. Age-Related Reductions in Cerebrovascular Reactivity Using 4D Flow MRI. Front Aging Neurosci 2019; 11:281. [PMID: 31680935 PMCID: PMC6811507 DOI: 10.3389/fnagi.2019.00281] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 10/01/2019] [Indexed: 12/12/2022] Open
Abstract
Cerebrovascular reactivity (CVR), is important for determining future risk of cerebrovascular disease. It is unclear if primary aging is associated with reductions in CVR because previous studies often include participants with vascular risk factors. Additionally, the inconsistency in the literature may be due to the inherent difficulty in quantifying intracranial cerebral blood flow and CVR. To address these limitations, we determined the effect of age on CVR in the large intracranial vessels in adults with low vascular risk using state-of-the-art MRI techniques. We also determined if the effect of age on CVR was sex-specific. Young (n = 20; 25 ± 3 years) and older (n = 19; 61 ± 5 years) healthy, physically active adults participated in the study. CVR was measured in response to hypercapnia using 4D flow MRI, which allows for simultaneous angiographic and quantitative blood flow measurements in the intracranial arteries. Older adults had lower global CVR and CVR in multiple intracranial arteries [right and left internal carotid arteries (ICA), right and left middle cerebral arteries (MCA), and basilar artery (BA)] compared with young adults (p < 0.05 for all). In addition, the MCA dilated significantly in response to hypercapnia in young (p < 0.05), but not older adults. Young men demonstrated higher global CVR and CVR in multiple intracranial arteries (ICAs, MCAs, and BA) compared with young women and older men (p < 0.05 for both); however, CVR did not differ between young women and older women. Our results demonstrate that, using 4D flow MRI, primary aging is associated with lower CVR in adults with low vascular risk. In addition, the effect of age on CVR may be driven by men. The 4D flow MRI technique may provide a promising new alternative to measure cerebrovascular physiology without the limitations of commonly used techniques. Future studies could utilize this MRI technique to examine interventions to maintain CVR with advancing age. This study was registered under clinicaltrials.gov # NCT02840851.
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Affiliation(s)
- Kathleen B Miller
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, United States
| | - Anna J Howery
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, United States
| | - Leonardo A Rivera-Rivera
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Sterling C Johnson
- Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States.,William S. Middleton Memorial Veterans Hospital, Geriatric Research Education and Clinical Center, Madison, WI, United States
| | - Howard A Rowley
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States.,Wisconsin Alzheimer's Disease Research Center, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Oliver Wieben
- Department of Medical Physics, School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI, United States
| | - Jill N Barnes
- Bruno Balke Biodynamics Laboratory, Department of Kinesiology, University of Wisconsin-Madison, Madison, WI, United States
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Determining differences between critical closing pressure and resistance-area product: responses of the healthy young and old to hypocapnia. Pflugers Arch 2019; 471:1117-1126. [DOI: 10.1007/s00424-019-02290-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 05/31/2019] [Accepted: 06/05/2019] [Indexed: 10/26/2022]
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35
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Hoiland RL, Fisher JA, Ainslie PN. Regulation of the Cerebral Circulation by Arterial Carbon Dioxide. Compr Physiol 2019; 9:1101-1154. [DOI: 10.1002/cphy.c180021] [Citation(s) in RCA: 101] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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36
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Favre ME, Serrador JM. Sex differences in cerebral autoregulation are unaffected by menstrual cycle phase in young, healthy women. Am J Physiol Heart Circ Physiol 2019; 316:H920-H933. [DOI: 10.1152/ajpheart.00474.2018] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sex is known to affect the prevalence of conditions such as stroke. However, effects of sex on cerebral blood flow regulation are still not well understood. Critical to this understanding is how fluctuations in hormones across the menstrual cycle affect cerebral autoregulation. We measured autoregulation in the early follicular, late follicular, and midluteal phases during spontaneous and induced blood pressure oscillations in 26 young, healthy individuals (13 women and 13 men, age: 26 ± 4 yr). Men participated three times, ~1–3 wk apart. Beat-by-beat blood pressure, heart rate, end-tidal CO2, and transcranial Doppler ultrasonography of the middle (MCA) and anterior (ACA) cerebral arteries were obtained. We did not find a difference in cerebral autoregulation across the menstrual cycle in women but found significantly improved autoregulation in the MCA and ACA of women compared with men. Women demonstrated significantly lower MCA gain (0.97 ± 0.13 vs. 1.17 ± 0.14%/mmHg, P = 0.001), higher MCA phase (46.1 ± 12.6 vs. 35.8 ± 7.9°, P = 0.019), and higher ACA phase (40.5 ± 10.8 vs 31.5 ± 8.5°, P = 0.040) during repeated squat-to-stand maneuvers. Women also had lower MCA gain (1.50 ± 0.11 vs. 1.72 ± 0.30%/mmHg, P = 0.029) during spontaneous fluctuations in pressure while standing and less of a decrease in MCA flow velocity (−18.7 ± 2.7 vs. −23.2 ± 6.0%, P = 0.014) during sit-to-stand maneuvers. Our results suggest that young women have improved cerebral autoregulation compared with young men regardless of menstrual cycle phase and that autoregulation is relatively robust to acute fluctuations in female sex hormones. NEW & NOTEWORTHY This is the first study to investigate thoroughly the effects of menstrual cycle phase and sex differences in cerebral autoregulation in young, healthy individuals. Cerebral autoregulation was unaffected by menstrual cycle phase during both repeated squat-to-stand and sit-to-stand maneuvers. However, women demonstrated significantly improved cerebral autoregulation in the middle and anterior cerebral arteries, suggesting women were able to maintain cerebral blood flow during changes in blood pressure more efficiently than men.
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Affiliation(s)
- Michelle E. Favre
- Department of Pharmacology, Physiology and Neuroscience; Rutgers Biomedical and Health Sciences, Newark, New Jersey
| | - Jorge M. Serrador
- Department of Pharmacology, Physiology and Neuroscience; Rutgers Biomedical and Health Sciences, Newark, New Jersey
- War-Related Illness and Injury Study Center, Department of Veterans Affairs, East Orange, New Jersey
- Department of Cardiovascular Electronics, National University of Ireland Galway, Galway, Ireland
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37
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Joshi H, Edgell H. Sex differences in the ventilatory and cardiovascular response to supine and tilted metaboreflex activation. Physiol Rep 2019; 7:e14041. [PMID: 30916469 PMCID: PMC6436143 DOI: 10.14814/phy2.14041] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 03/08/2019] [Indexed: 12/26/2022] Open
Abstract
Women have attenuated exercise pressor responses compared to men; however, their cerebrovascular and ventilatory responses have not been previously measured. Furthermore, recent evidence has shown that posture change can influence the response of the metaboreflex but this has only been tested in men. Young and healthy men (n = 14; age: 21 ± 2) and women (n = 11; age: 19 ± 1) underwent 40% MVC static handgrip exercise (HG) for 2 min followed by 3 min of post-exercise circulatory occlusion (PECO) in the supine and 70° tilted postures. In supine position during HG and PECO only men had an increase in ventilation (Men: Baseline: 12.5 ± 1.7 L/min, HG: 18.6 ± 5.3 L/min, PECO: 17.7 ± 10.3 L/min; Women: Baseline: 12.0 ± 1.5 L/min, HG: 12.4 ± 1.2 L/min, PECO: 11.5 ± 1.3 L/min; Sex × Time interaction P = 0.037). In supine position during HG and PECO men and women had similar reductions in cerebrovascular conductance (Men: Baseline: 0.79 ± 0.13 cm/sec/mmHg, HG: 0.68 ± 0.18 cm/sec/mmHg, PECO: 0.61 ± 0.19 cm/s/mmHg; Women: Baseline: 0.87 ± 0.13 cm/sec/mmHg, HG: 0.83 ± 0.14 cm/sec/mmHg, PECO: 0.75 ± 0.17 cm/sec/mmHg; P < 0.015 HG/PECO vs. baseline). When comparing the response to PECO in the supine versus upright postures there was a significant attenuation in the increase in mean arterial pressure in both men and women (Supine posture: Men: +23.3 ± 14.5 mmHg, Women: +12.0 ± 7.3 mmHg; Upright posture: Men: +15.7 ± 14.1 mmHg, Women: +7.7 ± 6.7 mmHg; Main effect of sex P = 0.042, Main effect of posture P < 0.001). Our results indicate sexually dimorphic ventilatory responses to HG and PECO which could be due to different interactions of the metaboreflex and chemoreflex. We have also shown evidence of attenuated metaboreflex function in the upright posture in both men and women.
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Affiliation(s)
- Hitesh Joshi
- School of Kinesiology and Health SciencesYork UniversityTorontoOntarioCanada
| | - Heather Edgell
- School of Kinesiology and Health SciencesYork UniversityTorontoOntarioCanada
- Muscle Health Research CentreYork UniversityTorontoOntarioCanada
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38
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Labrecque L, Rahimaly K, Imhoff S, Paquette M, Le Blanc O, Malenfant S, Drapeau A, Smirl JD, Bailey DM, Brassard P. Dynamic cerebral autoregulation is attenuated in young fit women. Physiol Rep 2019; 7:e13984. [PMID: 30652420 PMCID: PMC6335382 DOI: 10.14814/phy2.13984] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 12/28/2018] [Indexed: 02/07/2023] Open
Abstract
Young women exhibit higher prevalence of orthostatic hypotension with presyncopal symptoms compared to men. These symptoms could be influenced by an attenuated ability of the cerebrovasculature to respond to rapid blood pressure (BP) changes [dynamic cerebral autoregulation (dCA)]. The influence of sex on dCA remains unclear. dCA in 11 fit women (25 ± 2 years) and 11 age-matched men (24 ± 1 years) was compared using a multimodal approach including a sit-to-stand (STS) and forced BP oscillations (repeated squat-stand performed at 0.05 and 0.10 Hz). Prevalence of initial orthostatic hypotension (IOH; decrease in systolic ≥ 40 mmHg and/or diastolic BP ≥ 20 mmHg) during the first 15 sec of STS was determined as a functional outcome. In women, the decrease in mean middle cerebral artery blood velocity (MCAvmean ) following the STS was greater (-20 ± 8 vs. -11 ± 7 cm sec-1 ; P = 0.018) and the onset of the regulatory change (time lapse between the beginning of the STS and the increase in the conductance index (MCAvmean /mean arterial pressure) was delayed (P = 0.007). Transfer function analysis gain during 0.05 Hz squat-stand was ~48% higher in women (6.4 ± 1.3 vs. 3.8 ± 2.3 cm sec-1 mmHg-1 ; P = 0.017). Prevalence of IOH was comparable between groups (women: 4/9 vs. men: 5/9, P = 0.637). These results indicate the cerebrovasculature of fit women has an attenuated ability to react to rapid changes in BP in the face of preserved orthostasis, which could be related to higher resting cerebral blood flow allowing women to better face transient hypotension.
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Affiliation(s)
- Lawrence Labrecque
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Kevan Rahimaly
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Sarah Imhoff
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Myriam Paquette
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Olivier Le Blanc
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Simon Malenfant
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Audrey Drapeau
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
| | - Jonathan D. Smirl
- Concussion Research LaboratoryHealth and Exercise SciencesUniversity of British Columbia OkanaganBritish ColumbiaCanada
| | - Damian M. Bailey
- Neurovascular Research LaboratoryFaculty of Life Sciences and EducationUniversity of South WalesSouth WalesUnited Kingdom
| | - Patrice Brassard
- Department of KinesiologyFaculty of MedicineUniversité LavalQuébecCanada
- Research center of the Institut universitaire de cardiologie et de pneumologie de QuébecQuébecCanada
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Hazlett C, Edgell H. Chemoreflex function and brain blood flow during upright posture in men and women. Physiol Rep 2018; 6. [PMID: 29333725 PMCID: PMC5789659 DOI: 10.14814/phy2.13571] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 12/09/2017] [Indexed: 11/24/2022] Open
Abstract
Orthostatic intolerance is more common in women than men, and some studies have found that women in the early follicular (EF) phase of the menstrual cycle experience the greatest feelings of lightheadedness. Chemoreflex function while supine or upright was investigated to determine the potential contribution of ventilatory control to these phenomena. Men (n = 13) and women (n = 14) were tested while supine and 70° upright (head-up tilt [HUT]) and given: (1) normoxia or (2) hypercapnia (5% CO2 ). Women were tested during the EF phase (days 2-5) and the midluteal phase (ML; days 18-24). During HUT, all groups reduced cerebrovascular resistance index (men: 1.45 ± 0.08 to 1.42 ± 0.07 mmHg/(cm·sec), EF: 1.38 ± 0.11 to 1.26 ± 0.10 mmHg/(cm·sec), ML: 1.25 ± 0.07 to 1.09 ± 0.07 mmHg/(cm·sec); P ≤ 0.019); however, only men increased ventilation (men: 11.99 ± 0.65 to 13.24 ± 0.83 L/min; P < 0.01). In response to hypercapnia in the supine position, men had a smaller increase of diastolic middle cerebral artery velocity compared to women in the ML phase (men: +9.1 ± 2.0 cm/sec, ML: +15.7 ± 3.1 cm/sec, P = 0.039). During hypercapnia in HUT (compared to hypercapnia while supine), all groups had an augmented increase of ventilation (men: +7.46 ± 1.34 vs. +5.84 ± 1.09 L/min, EF: +6.71 ± 0.83 vs. +5.48 ± 0.66 L/min, ML: +7.99 ± 1.13 vs. +5.65 ± 0.81 L/min; P ≤ 0.028), suggesting that all groups experienced augmentation of the CO2 chemoreflex; however, only men had an augmented increase of mean arterial pressure (+0.10 ± 0.58 to +4.71 ± 0.87 mmHg; P ≤ 0.017). Our results indicate that men have different ventilatory responses to upright tilt compared to women, and that the CO2 chemoreflex response is enhanced in upright posture in both sexes. Furthermore, sexually dimorphic blood pressure responses to this chemoreflex enhancement are evident.
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Affiliation(s)
- Christopher Hazlett
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada
| | - Heather Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada.,Muscle Health Research Centre, York University, Toronto, Ontario, Canada
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Teixeira SC, Madureira JB, Azevedo EI, Castro PM. Ageing affects the balance between central and peripheral mechanisms of cerebrovascular regulation with increasing influence of systolic blood pressure levels. Eur J Appl Physiol 2018; 119:519-529. [PMID: 30467594 DOI: 10.1007/s00421-018-4036-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Accepted: 11/15/2018] [Indexed: 01/02/2023]
Abstract
BACKGROUND Arterial baroreflex (BR) and cerebral autoregulation (CA) are two major regulatory mechanisms that maintain constant cerebral perfusion. Little is known about the interplay between these mechanisms, particularly when considering the effects of ageing or sex. PURPOSE We studied the relationship between dynamic CA and BR sensitivity (BRS) in healthy subjects by sex and in different age strata. METHODS 95 healthy adults (52% female), 20-80 years-old, were recruited. Arterial blood pressure (Finometer), 3-lead electrocardiogram and cerebral blood flow velocity in middle cerebral arteries (transcranial Doppler) were monitored. We assessed CA by transfer function analysis and BRS in frequency and time domain. RESULTS With increasing age, BRS diminished (ANCOVA R2 = 0.281, p < 0.001) but CA parameters did not change significantly (p > 0.05). Overall, there was an inverse relationship between the efficacy of BRS and CA low-frequency gain [multivariate linear regression β = 0.41 (0.31; 0.61), p < 0.001]. However, this association suffers changes with ageing: in older subjects BRS and CA were not correlated [β = 0.10 (- 0.41; 0.62), p = 0.369]. Instead, decreasing systolic blood pressure correlated with less efficient CA [lower CA low-frequency gain β = - 0.02 (- 0.03; - 0.02), p = 0.003]. Sex did not affect BRS and CA relationship. CONCLUSIONS Cerebral blood supply is governed by a tuned balance between BR and CA which is lost with age as BRS decreases dramatically. Low systolic blood pressure values might be harmful to older subjects as they might reduce the ability to keep cerebral blood flow tightly controlled.
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Affiliation(s)
- Sofia Cunha Teixeira
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.
| | - João Brandão Madureira
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal
| | - Elsa Irene Azevedo
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.,Cardiovascular Research and Development Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Neurology, São João Hospital Centre, Porto, Portugal
| | - Pedro Miguel Castro
- Department of Clinical Neurosciences and Mental Health, Faculty of Medicine, University of Porto, Alameda Professor Hernâni Monteiro, 4200-319, Porto, Portugal.,Cardiovascular Research and Development Centre, Faculty of Medicine, University of Porto, Porto, Portugal.,Department of Neurology, São João Hospital Centre, Porto, Portugal
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Minhas JS, Panerai RB, Robinson TG. Sex differences in cerebral haemodynamics across the physiological range of PaCO 2. Physiol Meas 2018; 39:105009. [PMID: 30256215 DOI: 10.1088/1361-6579/aae469] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Cerebral blood flow (CBF) is influenced by changes in arterial CO2 (PaCO2). Recently, cerebral haemodynamic parameters were demonstrated to follow a four parameter logistic curve offering simultaneous assessment of dCA and CO2 vasoreactivity. However, the effects of sex on cerebral haemodynamics have yet to be described over a wide range of PaCO2. APPROACH CBF velocity (CBFV, transcranial Doppler), blood pressure (BP, Finometer) and end-tidal CO2 (EtCO2, capnography) were measured in healthy volunteers at baseline, and in response to hypo- (-5 mmHg and -10 mmHg below baseline) and hypercapnia (5% and 8% CO2), applied in random order. MAIN RESULTS Forty-five subjects (19 male, 26 female, mean age 37.5 years) showed significant differences between males and females in CBFV (50.9 ± 10.4 versus 61.5 ± 12.3 cm · s-1, p = 0.004), EtCO2 (39.2 ± 2.8 versus 36.9 ± 3.0 mmHg, p = 0.005), RAP (1.16 ± 0.23 versus 0.94 ± 0.40 mmHg cm · s-1, p = 0.005) and systolic BP (125.2 ± 8.0 versus 114.6 ± 12.4 mmHg, p = 0.0372), respectively. Significant differences between sexes were observed in the four logistic parameters: y min, y max, k (exponential coefficient) and x (EtCO2 level) across the haemodynamic variables. Significant differences included the CBFV-EtCO2 and ARI-EtCO2 relationship; ARImin (p = 0.036) and CBFVmax (p = 0.001), respectively. Furthermore, significant differences were observed for both CrCPmin (p = 0.045) and CrCPmax (p = 0.005) and RAPmin (p < 0.001) and RAPmax (p < 0.001). SIGNIFICANCE This is the first study to examine sex individually within the context of a multi-level CO2 protocol. The demonstration that the logistic curve parameters are influenced by sex, highlights the need to take into account sex differences between participants in both physiological and clinical studies.
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Affiliation(s)
- J S Minhas
- Cerebral Haemodynamics in Ageing and Stroke Medicine (CHIASM) Research Group, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom. Author to whom any correspondence should be addressed
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Abstract
Sex and gender, as biological and social factors, significantly influence health outcomes. Among the biological factors, sex differences in vascular physiology may be one specific mechanism contributing to the observed differences in clinical presentation, response to treatment, and clinical outcomes in several vascular disorders. This review focuses on the cerebrovascular bed and summarizes the existing literature on sex differences in cerebrovascular hemodynamics to highlight the knowledge deficit that exists in this domain. The available evidence is used to generate mechanistically plausible and testable hypotheses to underscore the unmet need in understanding sex-specific mechanisms as targets for more effective therapeutic and preventive strategies.
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Affiliation(s)
- Cristina Duque
- Division of Stroke and Neurocritical Care, Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.,Department of Neurology, Coimbra University Hospital Center, Coimbra, Portugal
| | - Steven K Feske
- Division of Stroke, Department of Neurology, Brigham and Women's Hospital, Boston, Massachusetts
| | - Farzaneh A Sorond
- Division of Stroke and Neurocritical Care, Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois
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Influence of sex, menstrual cycle, and oral contraceptives on the cerebrovascular response to paced deep breathing. Clin Auton Res 2017; 27:411-415. [PMID: 28766085 DOI: 10.1007/s10286-017-0455-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Accepted: 07/20/2017] [Indexed: 10/19/2022]
Abstract
PURPOSE Deep breathing assesses autonomic function; however, many researchers/clinicians do not account for hyperventilation, brain blood flow or blood pressure. METHODS Men and women (with/without oral contraceptives) participated. women participated during low and high hormone phases of the menstrual cycle. Blood pressure, end-tidal carbon dioxide, middle cerebral artery velocity and cerebrovascular resistance were assessed. RESULTS Deep breathing decreased end-tidal carbon dioxide and middle cerebral artery velocity while increasing cerebrovascular resistance in all participants; blood pressure decreased in men. There were no influences of menstrual cycle or oral contraceptives. CONCLUSIONS Men have different autonomic responses to deep breathing compared to women.
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Abidi S, Nili M, Serna S, Kim S, Hazlett C, Edgell H. Influence of sex, menstrual cycle, and oral contraceptives on cerebrovascular resistance and cardiorespiratory function during Valsalva or standing. J Appl Physiol (1985) 2017; 123:375-386. [PMID: 28522756 DOI: 10.1152/japplphysiol.00035.2017] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 05/11/2017] [Accepted: 05/16/2017] [Indexed: 01/11/2023] Open
Abstract
Women experience orthostatic intolerance more than men, and they experience faintness more in the early follicular [i.e., low-hormone (LH)] than luteal [i.e., high-hormone (HH)] phase of the menstrual cycle. Men (n = 13, 25.8 ± 1.8 yr old) and women in the LH (days 2-5; placebo) and HH (days 18-24; high dose) phases of the menstrual cycle with (OC; n = 14, 22.0 ± 0.8 yr old) or without (NOC; n = 12, 21.8 ± 0.5 yr old) oral contraceptive (OC) use underwent the Valsalva maneuver and a supine-sit-stand protocol. Blood pressure, normalized stroke volume [stroke volume index (SVi)], cardiac output index, heart rate, end-tidal CO2, and middle cerebral artery (MCA) blood flow velocity were measured. When subjected to the Valsalva maneuver, all women had a greater increase in diastolic and mean MCA blood flow velocity than men (P ≤ 0.065), with no significant effect of menstrual cycle phase or OC use. When subjected to the supine-sit-stand protocol, men had lower MCA blood flow velocity (P < 0.038) than all women, and SVi was higher in men than in the NOC group in all postures (P < 0.011) and in the OC group in the LH phase of the menstrual cycle during standing (P = 0.010). Only men experienced higher resistance index (P < 0.001) and pulsatility index (P < 0.001) with standing. The OC group had lower end-tidal CO2 (P = 0.002) than the NOC group (P = 0.030) and men (P ≤ 0.067). SVi (P = 0.004) and cardiac output index (P = 0.008) were higher in the OC than NOC group. A tendency toward a lower mean MCA blood flow velocity (P = 0.058) and higher SVi (P = 0.059) and pulsatility index (P = 0.058) was noted in the HH than LH phase. Mean arterial pressure was higher in the OC than NOC group in the LH phase (P = 0.049) and lower in the HH than LH phase (P = 0.014). Our results indicate that cycling estrogens/progestins can influence ventilatory, cardiovascular, and/or cerebrovascular physiology.NEW & NOTEWORTHY We have found sex differences in the cerebrovascular response to the Valsalva maneuver and standing. Men have greater cerebral vasoconstriction (or women have greater cerebral vasodilation) during late phase II of the Valsalva maneuver, and the cerebrovascular resistance index increases in men, but not in women, during standing. Furthermore, our findings indicate that both the menstrual cycle phase and oral contraceptive use can influence cardiovascular function both at rest and during active standing.
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Affiliation(s)
- Syed Abidi
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Misha Nili
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Stephania Serna
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Simon Kim
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Christopher Hazlett
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and
| | - Heather Edgell
- School of Kinesiology and Health Sciences, York University, Toronto, Ontario, Canada; and .,Muscle Health Research Centre, York University, Toronto, Ontario, Canada
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45
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Bronzwaer ASGT, Verbree J, Stok WJ, Daemen MJAP, van Buchem MA, van Osch MJP, van Lieshout JJ. The cerebrovascular response to lower-body negative pressure vs. head-up tilt. J Appl Physiol (1985) 2017; 122:877-883. [PMID: 28082333 DOI: 10.1152/japplphysiol.00797.2016] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2016] [Revised: 01/05/2017] [Accepted: 01/05/2017] [Indexed: 11/22/2022] Open
Abstract
Lower-body negative pressure (LBNP) has been proposed as a MRI-compatible surrogate for orthostatic stress. Although the effects of LBNP on cerebral hemodynamic behavior have been considered to reflect those of orthostatic stress, a direct comparison with actual orthostasis is lacking. We assessed the effects of LBNP (-50 mmHg) vs. head-up tilt (HUT; at 70°) in 10 healthy subjects (5 female) on transcranial Doppler-determined cerebral blood flow velocity (CBFv) in the middle cerebral artery and cerebral perfusion pressure (CPP) as estimated from the blood pressure signal (finger plethysmography). CPP was maintained during LBNP but decreased after 2 min in response to HUT, leading to an ~15% difference in CPP between LBNP and HUT (P ≤ 0.020). Mean CBFv initially decreased similarly in response to LBNP and for HUT, but, from minute 3 on, the decline became ~50% smaller (P ≤ 0.029) during LBNP. The reduction in end-tidal Pco2 partial pressure (PetCO2 ) was comparable but with an earlier return toward baseline values in response to LBNP but not during HUT (P = 0.008). We consider the larger decrease in CBFv during HUT vs. LBNP attributable to the pronounced reduction in PetCO2 and to gravitational influences on CPP, and this should be taken into account when applying LBNP as an MRI-compatible orthostatic stress modality.NEW & NOTEWORTHY Lower-body negative pressure (LBNP) has the potential to serve as a MRI-compatible surrogate of orthostatic stress but a comparison with actual orthostasis was lacking. This study showed that the pronounced reduction in end-tidal Pco2 together with gravitational effects on the brain circulation lead to a larger decline in cerebral blood flow velocity in response to head-up tilt than during lower-body negative pressure. This should be taken into account when employing lower-body negative pressure as MRI-compatible alternative to orthostatic stress.
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Affiliation(s)
- Anne-Sophie G T Bronzwaer
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Jasper Verbree
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Wim J Stok
- Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - Mat J A P Daemen
- Department of Pathology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; and
| | - Mark A van Buchem
- Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands
| | | | - Johannes J van Lieshout
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; .,Laboratory for Clinical Cardiovascular Physiology, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Department of Anatomy, Embryology and Physiology, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.,Medical Research Center/Arthritis Research United Kingdom Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, United Kingdom
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46
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Liu J, Liu Y, Ren LH, Li L, Wang Z, Liu SS, Li SZ, Cao TS. Effects of race and sex on cerebral hemodynamics, oxygen delivery and blood flow distribution in response to high altitude. Sci Rep 2016; 6:30500. [PMID: 27503416 PMCID: PMC4977556 DOI: 10.1038/srep30500] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Accepted: 07/06/2016] [Indexed: 11/25/2022] Open
Abstract
To assess racial, sexual, and regional differences in cerebral hemodynamic response to high altitude (HA, 3658 m). We performed cross-sectional comparisons on total cerebral blood flow (TCBF = sum of bilateral internal carotid and vertebral arterial blood flows = QICA + QVA), total cerebrovascular resistance (TCVR), total cerebral oxygen delivery (TCOD) and QVA/TCBF (%), among six groups of young healthy subjects: Tibetans (2-year staying) and Han (Han Chinese) at sea level, Han (2-day, 1-year and 5-year) and Tibetans at HA. Bilateral ICA and VA diameters and flow velocities were derived from duplex ultrasonography; and simultaneous measurements of arterial pressure, oxygen saturation, and hemoglobin concentration were conducted. Neither acute (2-day) nor chronic (>1 year) responses showed sex differences in Han, except that women showed lower TCOD compared with men. Tibetans and Han exhibited different chronic responses (percentage alteration relative to the sea-level counterpart value) in TCBF (−17% vs. 0%), TCVR (22% vs. 12%), TCOD (0% vs. 10%) and QVA/TCBF (0% vs. 2.4%, absolute increase), with lower resting TCOD found in SL- and HA-Tibetans. Our findings indicate racial but not sex differences in cerebral hemodynamic adaptations to HA, with Tibetans (but not Han) demonstrating an altitude-related change of CBF distribution.
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Affiliation(s)
- Jie Liu
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Yang Liu
- Department of Cardiovascular Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Li-Hua Ren
- General Hospital of Tibet Military Area Command, Lhasa, Tibet Autonomous Region, China
| | - Li Li
- Department of Ultrasonic Medicine, Affiliated Hospital of Tibet University for Nationalities, Xianyang, Shaanxi, China
| | - Zhen Wang
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Shan-Shan Liu
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
| | - Su-Zhi Li
- General Hospital of Tibet Military Area Command, Lhasa, Tibet Autonomous Region, China
| | - Tie-Sheng Cao
- Department of Ultrasound Diagnostics, Tangdu Hospital, Fourth Military Medical University, Xi'an, Shaanxi, China
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47
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Boulet LM, Tymko MM, Jamieson AN, Ainslie PN, Skow RJ, Day TA. Influence of prior hyperventilation duration on respiratory chemosensitivity and cerebrovascular reactivity during modified hyperoxic rebreathing. Exp Physiol 2016; 101:821-35. [DOI: 10.1113/ep085706] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/16/2016] [Indexed: 12/30/2022]
Affiliation(s)
- Lindsey M. Boulet
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Michael M. Tymko
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Alenna N. Jamieson
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Rachel J. Skow
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Trevor A. Day
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
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da Costa L, van Niftrik CB, Crane D, Fierstra J, Bethune A. Temporal Profile of Cerebrovascular Reactivity Impairment, Gray Matter Volumes, and Persistent Symptoms after Mild Traumatic Head Injury. Front Neurol 2016; 7:70. [PMID: 27242655 PMCID: PMC4862985 DOI: 10.3389/fneur.2016.00070] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 04/25/2016] [Indexed: 12/25/2022] Open
Abstract
Objective Increased awareness around neurocognitive deficits after mild traumatic brain injury (mTBI) has progressed the search for objective, diagnostic, and monitoring tools, yet imaging biomarkers for mTBI and recovery are not established in clinical use. It has been suggested that mTBI impairs cerebrovascular reactivity (CVR) to CO2, which could be related to post-concussive syndrome (PCS). We investigate CVR evolution after mTBI using blood-oxygen-level dependent (BOLD) magnetic resonance imaging (MRI) and possible correlation with PCS. Methods A prospective cohort of 25 mTBI patients and 18 matched controls underwent BOLD MRI CVR measurements. A subset of 19 mTBI patients underwent follow-up testing. Visits took place at a mean of 63 and 180 days after injury. Symptoms were assessed with the Sport Concussion Assessment Tool 2 (SCAT2). Symptoms, CVR and brain volume [gray matter (GM), white matter (WM), and whole brain (WB)], age, and sex, were examined between groups and longitudinally within traumatic brain injury (TBI) patients. Results Traumatic brain injury participants were 72% males, mean age being 42.7 years. Control participants were 61% with mean age of 38.7 years. SCAT2 scores tended to improve among those mTBI patients with follow-up visits (p = 0.07); however, they did not tend to recover to scores of the healthy controls. Brain volumes were not statistically different between groups at the first visit (WM p = 0.71; GM p = 0.36). In mTBI patients, there was a reduction in GM volume between visits 1 and 2 (p = 0.0046). Although mean CVR indexes were similar (WM p = 0.27; GM p = 0.36; and WB p = 0.35), the correlation between SCAT2 and CVR was negative in controls (WM-r = −0.59; p = 0.010; GM-r = −0.56; p = 0.016; brain-r = −0.58; p = 0.012) and weaker and positive in mTBI (brain-r = 0.4; p = 0.046; GM-r = 0.4; p = 0.048). SCAT2 correlated with GM volume (r = 0.5215, p = 0.0075) in mTBI but not in controls (r = 0.2945, p = 0.2355). Conclusion There is a correlation between lower GM CVR indexes and lower performance on SCAT2 in patients with mTBI, which seems to be associated with more symptoms. This correlation seems to persist well beyond 120 days. mTBI may lead to a decrease in GM volume in these patients.
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Affiliation(s)
- Leodante da Costa
- Division of Neurosurgery, Department of Surgery, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada; Department of Medical Imaging, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, ON, Canada
| | | | - David Crane
- Brain Sciences Program, Sunnybrook Research Institute , Toronto, ON , Canada
| | - Jorn Fierstra
- Division of Neurosurgery, University Hospital Zurich , Zurich , Switzerland
| | - Allison Bethune
- Division of Neurosurgery, Department of Surgery, Sunnybrook Health Sciences Centre, University of Toronto , Toronto, ON , Canada
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Cerebrovascular reactivity after treatment of unruptured intracranial aneurysms — A transcranial Doppler sonography and acetazolamide study. J Neurol Sci 2016; 363:97-103. [DOI: 10.1016/j.jns.2015.12.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2015] [Revised: 12/11/2015] [Accepted: 12/14/2015] [Indexed: 11/19/2022]
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50
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Sobczyk O, Crawley AP, Poublanc J, Sam K, Mandell DM, Mikulis DJ, Duffin J, Fisher JA. Identifying Significant Changes in Cerebrovascular Reactivity to Carbon Dioxide. AJNR Am J Neuroradiol 2016; 37:818-24. [PMID: 26846924 DOI: 10.3174/ajnr.a4679] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 10/23/2015] [Indexed: 01/04/2023]
Abstract
BACKGROUND AND PURPOSE Changes in cerebrovascular reactivity can be used to assess disease progression and response to therapy but require discrimination of pathology from normal test-to-test variability. Such variability is due to variations in methodology, technology, and physiology with time. With uniform test conditions, our aim was to determine the test-to-test variability of cerebrovascular reactivity in healthy subjects and in patients with known cerebrovascular disease. MATERIALS AND METHODS Cerebrovascular reactivity was the ratio of the blood oxygen level-dependent MR imaging response divided by the change in carbon dioxide stimulus. Two standardized cerebrovascular reactivity tests were conducted at 3T in 15 healthy men (36.7 ± 16.1 years of age) within a 4-month period and were coregistered into standard space to yield voxelwise mean cerebrovascular reactivity interval difference measures, composing a reference interval difference atlas. Cerebrovascular reactivity interval difference maps were prepared for 11 male patients. For each patient, the test-retest difference of each voxel was scored statistically as z-values of the corresponding voxel mean difference in the reference atlas and then color-coded and superimposed on the anatomic images to create cerebrovascular reactivity interval difference z-maps. RESULTS There were no significant test-to-test differences in cerebrovascular reactivity in either gray or white matter (mean gray matter, P = .431; mean white matter, P = .857; paired t test) in the healthy cohort. The patient cerebrovascular reactivity interval difference z-maps indicated regions where cerebrovascular reactivity increased or decreased and the probability that the changes were significant. CONCLUSIONS Accounting for normal test-to-test differences in cerebrovascular reactivity enables the assessment of significant changes in disease status (stability, progression, or regression) in patients with time.
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Affiliation(s)
- O Sobczyk
- From the Institute of Medical Science (O.S., D.J.M., J.A.F.)
| | - A P Crawley
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory (A.P.C., J.P., K.S., D.M.M., D.J.M.)
| | - J Poublanc
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory (A.P.C., J.P., K.S., D.M.M., D.J.M.)
| | - K Sam
- Department of Physiology (K.S., J.D., J.A.F.), University of Toronto, Toronto, Canada Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory (A.P.C., J.P., K.S., D.M.M., D.J.M.)
| | - D M Mandell
- Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory (A.P.C., J.P., K.S., D.M.M., D.J.M.)
| | - D J Mikulis
- From the Institute of Medical Science (O.S., D.J.M., J.A.F.) Joint Department of Medical Imaging and the Functional Neuroimaging Laboratory (A.P.C., J.P., K.S., D.M.M., D.J.M.)
| | - J Duffin
- Department of Physiology (K.S., J.D., J.A.F.), University of Toronto, Toronto, Canada Department of Anaesthesia and Pain Management (J.D., J.A.F.), University Health Network, Toronto, Canada
| | - J A Fisher
- From the Institute of Medical Science (O.S., D.J.M., J.A.F.) Department of Physiology (K.S., J.D., J.A.F.), University of Toronto, Toronto, Canada Department of Anaesthesia and Pain Management (J.D., J.A.F.), University Health Network, Toronto, Canada
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