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Taboni A, Fagoni N, Fontolliet T, Vinetti G, Ferretti G. Baroreflex dynamics during the rest to exercise transient in acute normobaric hypoxia in humans. Eur J Appl Physiol 2024:10.1007/s00421-024-05485-4. [PMID: 38656378 DOI: 10.1007/s00421-024-05485-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2024] [Accepted: 03/26/2024] [Indexed: 04/26/2024]
Abstract
PURPOSE We hypothesised that during a rest-to-exercise transient in hypoxia (H), compared to normoxia (N), (i) the initial baroreflex sensitivity (BRS) decrease would be slower and (ii) the fast heart rate (HR) and cardiac output (CO) response would have smaller amplitude (A1) due to lower vagal activity in H than N. METHODS Ten participants performed three rest-to-50 W exercise transients on a cycle-ergometer in N (ambient air) and three in H (inspired fraction of O2 = 0.11). R-to-R interval (RRi, by electrocardiography) and blood pressure profile (by photo-plethysmography) were recorded non-invasively. Analysis of the latter provided mean arterial pressure (MAP) and stroke volume (SV). CO = HR·SV. BRS was calculated by modified sequence method. RESULTS Upon exercise onset in N, MAP fell to a minimum (MAPmin) then recovered. BRS decreased immediately from 14.7 ± 3.6 at rest to 7.0 ± 3.0 ms mmHg-1 at 50 W (p < 0.01). The first BRS sequence detected at 50 W was 8.9 ± 4.8 ms mmHg-1 (p < 0.05 vs. rest). In H, MAP showed several oscillations until reaching a new steady state. BRS decreased rapidly from 10.6 ± 2.8 at rest to 2.9 ± 1.5 ms mmHg-1 at 50 W (p < 0.01), as the first BRS sequence at 50 W was 5.8 ± 2.6 ms mmHg-1 (p < 0.01 vs. rest). CO-A1 was 2.96 ± 1.51 and 2.31 ± 0.94 l min-1 in N and H, respectively (p = 0.06). HR-A1 was 7.7 ± 4.6 and 7.1 ± 5.9 min-1 in N and H, respectively (p = 0.81). CONCLUSION The immediate BRS decrease in H, coupled with similar rapid HR and CO responses, is compatible with a withdrawal of residual vagal activity in H associated with increased sympathetic drive.
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Affiliation(s)
- Anna Taboni
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, Brescia, Italy.
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland.
| | - Nazzareno Fagoni
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, Brescia, Italy
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland
| | - Timothée Fontolliet
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland
| | - Giovanni Vinetti
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, Brescia, Italy
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Guido Ferretti
- Department of Molecular and Translational Medicine, University of Brescia, Viale Europa 11, Brescia, Italy
- Department of Anaesthesiology, Pharmacology, Intensive Care, and Emergencies, University of Geneva, Geneva, Switzerland
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Hofmann GC, Gama de Barcellos Filho P, Khodadadi F, Ostrowski D, Kline DD, Hasser EM. Vagotomy blunts cardiorespiratory responses to vagal afferent stimulation via pre- and postsynaptic effects in the nucleus tractus solitarii. J Physiol 2024; 602:1147-1174. [PMID: 38377124 DOI: 10.1113/jp285854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 01/29/2024] [Indexed: 02/22/2024] Open
Abstract
Viscerosensory information travels to the brain via vagal afferents, where it is first integrated within the brainstem nucleus tractus solitarii (nTS), a critical contributor to cardiorespiratory function and site of neuroplasticity. We have shown that decreasing input to the nTS via unilateral vagus nerve transection (vagotomy) induces morphological changes in nTS glia and reduces sighs during hypoxia. The mechanisms behind post-vagotomy changes are not well understood. We hypothesized that chronic vagotomy alters cardiorespiratory responses to vagal afferent stimulation via blunted nTS neuronal activity. Male Sprague-Dawley rats (6 weeks old) underwent right cervical vagotomy caudal to the nodose ganglion, or sham surgery. After 1 week, rats were anaesthetized, ventilated and instrumented to measure mean arterial pressure (MAP), heart rate (HR), and splanchnic sympathetic and phrenic nerve activity (SSNA and PhrNA, respectively). Vagal afferent stimulation (2-50 Hz) decreased cardiorespiratory parameters and increased neuronal Ca2+ measured by in vivo photometry and in vitro slice imaging of nTS GCaMP8m. Vagotomy attenuated both these reflex and neuronal Ca2+ responses compared to shams. Vagotomy also reduced presynaptic Ca2+ responses to stimulation (Cal-520 imaging) in the nTS slice. The decrease in HR, SSNA and PhrNA due to nTS nanoinjection of exogenous glutamate also was tempered following vagotomy. This effect was not restored by blocking excitatory amino acid transporters. However, the blunted responses were mimicked by NMDA, not AMPA, nanoinjection and were associated with reduced NR1 subunits in the nTS. Altogether, these results demonstrate that vagotomy induces multiple changes within the nTS tripartite synapse that influence cardiorespiratory reflex responses to afferent stimulation. KEY POINTS: Multiple mechanisms within the nucleus tractus solitarii (nTS) contribute to functional changes following vagal nerve transection. Vagotomy results in reduced cardiorespiratory reflex responses to vagal afferent stimulation and nTS glutamate nanoinjection. Blunted responses occur via reduced presynaptic Ca2+ activation and attenuated NMDA receptor expression and function, leading to a reduction in nTS neuronal activation. These results provide insight into the control of autonomic and respiratory function, as well as the plasticity that can occur in response to nerve damage and cardiorespiratory disease.
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Affiliation(s)
- Gabrielle C Hofmann
- Comparative Medicine, University of Missouri, Columbia, Missouri, USA
- Area Pathobiology, University of Missouri, Columbia, Missouri, USA
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
| | - Procopio Gama de Barcellos Filho
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
| | - Fateme Khodadadi
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
| | - Daniela Ostrowski
- Department of Pharmacology, A.T. Still University, Kirksville, Missouri, USA
| | - David D Kline
- Area Pathobiology, University of Missouri, Columbia, Missouri, USA
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
- Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
| | - Eileen M Hasser
- Area Pathobiology, University of Missouri, Columbia, Missouri, USA
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri, USA
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri, USA
- Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri, USA
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Andrade DC, Arce‐Álvarez A, Salazar‐Ardiles C, Toledo C, Guerrero‐Henriquez J, Alvarez C, Vasquez‐Muñoz M, Izquierdo M, Millet GP. Hypoxic peripheral chemoreflex stimulation-dependent cardiorespiratory coupling is decreased in swimmer athletes. Physiol Rep 2024; 12:e15890. [PMID: 38195247 PMCID: PMC10776339 DOI: 10.14814/phy2.15890] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/07/2023] [Accepted: 11/21/2023] [Indexed: 01/11/2024] Open
Abstract
Swimmer athletes showed a decreased ventilatory response and reduced sympathetic activation during peripheral hypoxic chemoreflex stimulation. Based on these observations, we hypothesized that swimmers develop a diminished cardiorespiratory coupling due to their decreased hypoxic peripheral response. To resolve this hypothesis, we conducted a study using coherence time-varying analysis to assess the cardiorespiratory coupling in swimmer athletes. We recruited 12 trained swimmers and 12 control subjects for our research. We employed wavelet time-varying spectral coherence analysis to examine the relationship between the respiratory frequency (Rf ) and the heart rate (HR) time series during normoxia and acute chemoreflex activation induced by five consecutive inhalations of 100% N2 . Comparing swimmers to control subjects, we observed a significant reduction in the hypoxic ventilatory responses to N2 in swimmers (0.012 ± 0.001 vs. 0.015 ± 0.001 ΔVE /ΔVO2 , and 0.365 ± 0.266 vs. 1.430 ± 0.961 ΔVE /ΔVCO2 /ΔSpO2 , both p < 0.001, swimmers vs. control, respectively). Furthermore, the coherence at the LF cutoff during hypoxia was significantly lower in swimmers compared to control subjects (20.118 ± 3.502 vs. 24.935 ± 3.832 area under curve [AUC], p < 0.012, respectively). Our findings strongly indicate that due to their diminished chemoreflex control, swimmers exhibited a substantial decrease in cardiorespiratory coupling during hypoxic stimulation.
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Affiliation(s)
- David C. Andrade
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura (FIMEDALT), Departamento Biomedico, Facultad de Ciencias de la SaludUniversidad de AntofagastaAntofagastaChile
| | - Alexis Arce‐Álvarez
- Escuela de Kinesiología, Facultad de Odontología y Ciencias de la RehabilitaciónUniversidad San SebastiánSantiagoChile
| | - Camila Salazar‐Ardiles
- Exercise Applied Physiology Laboratory, Centro de Investigación en Fisiología y Medicina de Altura (FIMEDALT), Departamento Biomedico, Facultad de Ciencias de la SaludUniversidad de AntofagastaAntofagastaChile
- NavarrabiomedHospital Universitario de Navarra (UHN), Universidad Pública de Navarra (UPNA), IdiSNAPamplonaNavarraSpain
| | - Camilo Toledo
- Laboratory of Cardiorespiratory and Sleep Physiology. Institute of Physiology. Faculty of MedicineUniversidad Austral de ChileValdiviaChile
| | - Juan Guerrero‐Henriquez
- Centro de Investigación en Fisiología y Medicina de Altura (FIMEDALT), Departamento de Ciencias de la Rehabilitación y el Movimiento Humano, Facultad de Ciencias de la SaludUniversidad de AntofagastaAntofagastaChile
| | - Cristian Alvarez
- Exercise and Rehabilitation Sciences Institute, School of Physical Therapy, Faculty of Rehabilitation SciencesUniversidad Andres BelloSantiagoChile
| | - Manuel Vasquez‐Muñoz
- Dirección de Docencia de Especialidades Médicas, Dirección de Postgrado, Facultad de Medicina y Ciencias de la SaludUniversidad MayorSantiagoChile
| | - Mikel Izquierdo
- NavarrabiomedHospital Universitario de Navarra (UHN), Universidad Pública de Navarra (UPNA), IdiSNAPamplonaNavarraSpain
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Abstract
The cardiovascular response to exercise is largely determined by neurocirculatory control mechanisms that help to raise blood pressure and modulate vascular resistance which, in concert with regional vasodilatory mechanisms, promote blood flow to active muscle and organs. These neurocirculatory control mechanisms include a feedforward mechanism, known as central command, and three feedback mechanisms, namely, 1) the baroreflex, 2) the exercise pressor reflex, and 3) the arterial chemoreflex. The hemodynamic consequences of these control mechanisms result from their influence on the autonomic nervous system and subsequent alterations in cardiac output and vascular resistance. Although stimulation of the baroreflex inhibits sympathetic outflow and facilitates parasympathetic activity, central command, the exercise pressor reflex, and the arterial chemoreflex facilitate sympathetic activation and inhibit parasympathetic drive. Despite considerable understanding of the cardiovascular consequences of each of these mechanisms in isolation, the circulatory impact of their interaction, which occurs when various control systems are simultaneously activated (e.g., during exercise at altitude), has only recently been recognized. Although aging and cardiovascular disease (e.g., heart failure, hypertension) have both been recognized to alter the hemodynamic consequences of these regulatory systems, this review is limited to provide a brief overview on the action and interaction of neurocirculatory control mechanisms in health.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
| | - Kanokwan Bunsawat
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah, United States
- Geriatric Research, Education, and Clinical Center, George E. Wahlen Department of Veterans Affairs Medical Center, Salt Lake City, Utah, United States
- Division of Geriatrics, Department of Internal Medicine, University of Utah, Salt Lake City, Utah, United States
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Giovanelli L, Malacarne M, Pagani M, Biolo G, Mekjavic IB, Bernardelli G, Lucini D. Moderate Aerobic Exercise Reduces the Detrimental Effects of Hypoxia on Cardiac Autonomic Control in Healthy Volunteers. J Pers Med 2023; 13:jpm13040585. [PMID: 37108971 PMCID: PMC10146556 DOI: 10.3390/jpm13040585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/22/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
Physical inactivity increases cardiometabolic risk through a variety of mechanisms, among which alterations of immunological, metabolic, and autonomic control systems may play a pivotal role. Physical inactivity is frequently associated with other factors that may further worsen prognosis. The association between physical inactivity and hypoxia is particularly interesting and characterizes several conditions—whether physiological (e.g., residing or trekking at high altitude and space flights) or pathological (e.g., chronic cardiopulmonary diseases and COVID-19). In this randomized intervention study, we investigated the combined effects of physical inactivity and hypoxia on autonomic control in eleven healthy and physically active male volunteers, both at baseline (ambulatory) conditions and, in a randomized order, hypoxic ambulatory, hypoxic bedrest, and normoxic bedrest (i.e., a simple experimental model of physical inactivity). Autoregressive spectral analysis of cardiovascular variabilities was employed to assess cardiac autonomic control. Notably, we found hypoxia to be associated with an impairment of cardiac autonomic control, especially when combined with bedrest. In particular, we observed an impairment of indices of baroreflex control, a reduction in the marker of prevalent vagal control to the SA node, and an increase in the marker of sympathetic control to vasculature.
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Debiage RR, Más FED, Thomas LD, Wolfran L, Silva MM, Fukushima FB. DEXMEDETOMIDINE AND XYLAZINE IN SHEEP: A STUDY OF CARDIOPULMONARY, HEMATOLOGICAL, AND GASTROINTESTINAL EFFECTS. Small Rumin Res 2022. [DOI: 10.1016/j.smallrumres.2022.106863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Horiuchi M, Dobashi S, Kiuchi M, Fukuoka Y, Koyama K. Hypoxic-induced resting ventilatory and circulatory responses under multistep hypoxia is related to decline in peak aerobic capacity in hypoxia. J Physiol Anthropol 2022; 41:36. [PMID: 36280884 PMCID: PMC9590180 DOI: 10.1186/s40101-022-00310-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Accepted: 10/07/2022] [Indexed: 11/07/2022] Open
Abstract
Background Several factors have been shown to contribute to hypoxic-induced declined in aerobic capacity. In the present study, we investigated the effects of resting hypoxic ventilatory and cardiac responses (HVR and HCR) on hypoxic-induced declines in peak oxygen uptake (\documentclass[12pt]{minimal}
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\begin{document}$$\dot{\mathrm V}$$\end{document}V˙O2peak). Methods Peak oxygen uptakes was measured in normobaric normoxia (room air) and hypoxia (14.1% O2) for 10 young healthy men. The resting HVR and HCR were evaluated at multiple steps of hypoxia (1 h at each of 21, 18, 15 and 12% O2). Arterial desaturation (ΔSaO2) was calculate by the difference between SaO2 at normoxia—at each level of hypoxia (%). HVR was calculate by differences in pulmonary ventilation between normoxia and each level of hypoxia against ΔSaO2 (L min−1 %−1 kg−1). Similarly, HCR was calculated by differences in heart rate between normoxia and each level of hypoxia against ΔSaO2 (beats min−1 %−1). Results \documentclass[12pt]{minimal}
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\begin{document}$$\dot{\mathrm V}$$\end{document}V˙O2peak significantly decreased in hypoxia by 21% on average (P < 0.001). HVR was not associated with changes in \documentclass[12pt]{minimal}
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\begin{document}$$\dot{\mathrm V}$$\end{document}V˙O2peak. ΔSaO2 from normoxia to 18% or 15% O2 and HCR between normoxia and 12% O2 were associated with changes in \documentclass[12pt]{minimal}
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\begin{document}$$\dot{\mathrm V}$$\end{document}V˙O2peak (P < 0.05, respectively). The most optimal model using multiple linear regression analysis found that ΔHCR at 12% O2 and ΔSaO2 at 15% O2 were explanatory variables (adjusted R2 = 0.580, P = 0.02). Conclusion These results suggest that arterial desaturation at moderate hypoxia and heart rate responses at severe hypoxia may account for hypoxic-induced declines in peak aerobic capacity, but ventilatory responses may be unrelated.
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Affiliation(s)
- Masahiro Horiuchi
- grid.419589.80000 0001 0725 4036Faculty of Sports and Life Science, National Institute of Fitness and Sports in Kanoya, Shiromizu town 1, Kanoya city, Kagoshima, 8912393 Japan ,Division of Human Environmental Science, Mt. Fuji Research Institute, Kami-yoshida 5597-1, Fuji-yoshida city, Yamanashi, 4030005 Japan
| | - Shohei Dobashi
- grid.267500.60000 0001 0291 3581Graduate School of Education, University of Yamanashi, Takeda 4-4-37, Kofu city, Yamanashi, 4008510 Japan ,grid.258269.20000 0004 1762 2738Graduate School of Health and Sports Science, Juntendo University, Hiraka-gakuendai 1-1, Inzai city, Chiba, 2701695 Japan
| | - Masataka Kiuchi
- grid.267500.60000 0001 0291 3581Graduate School Department of Interdisciplinary Research, University of Yamanashi, Takeda 4-4-37, Kofu city, Yamanashi, 4008510 Japan
| | - Yoshiyuki Fukuoka
- grid.255178.c0000 0001 2185 2753Faculty of Health and Sports Science, Doshisha University, Tatara-miyakodani 1-3, Kyotanabe city, Kyoto, 6100394 Japan
| | - Katsuhiro Koyama
- grid.267500.60000 0001 0291 3581Graduate School Department of Interdisciplinary Research, University of Yamanashi, Takeda 4-4-37, Kofu city, Yamanashi, 4008510 Japan ,grid.444168.b0000 0001 2161 7710Faculty of Sport Science, Yamanashi Gakuin University, Sakaori 2-4-5, Kofu city, Yamanashi, 4008575 Japan
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Berthelsen LF, van Diepen S, Steele AR, Vanden Berg ER, Bird J, Thrall S, Skalk A, Byman B, Pentz B, Wilson RJA, Jendzjowsky NG, Day TA, Steinback CD. Duration at high altitude influences the onset of arrhythmogenesis during apnea. Eur J Appl Physiol 2021; 122:475-487. [PMID: 34800158 DOI: 10.1007/s00421-021-04842-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/04/2021] [Indexed: 10/19/2022]
Abstract
PURPOSE Autonomic control of the heart is balanced by sympathetic and parasympathetic inputs. Excitation of both sympathetic and parasympathetic systems occurs concurrently during certain perturbations such as hypoxia, which stimulate carotid chemoreflex to drive ventilation. It is well established that the chemoreflex becomes sensitized throughout hypoxic exposure; however, whether progressive sensitization alters cardiac autonomic activity remains unknown. We sought to determine the duration of hypoxic exposure at high altitude necessary to unmask cardiac arrhythmias during instances of voluntary apnea. METHODS Measurements of steady-state chemoreflex drive (SS-CD), continuous electrocardiogram (ECG) and SpO2 (pulse oximetry) were collected in 22 participants on 1 day at low altitude (1045 m) and over eight consecutive days at high-altitude (3800 m). SS-CD was quantified as ventilation (L/min) over stimulus index (PETCO2/SpO2). RESULTS Bradycardia during apnea was greater at high altitude compared to low altitude for all days (p < 0.001). Cardiac arrhythmias occurred during apnea each day but became most prevalent (> 50%) following Day 5 at high altitude. Changes in saturation during apnea and apnea duration did not affect the magnitude of bradycardia during apnea (ANCOVA; saturation, p = 0.15 and apnea duration, p = 0.988). Interestingly, the magnitude of bradycardia was correlated with the incidence of arrhythmia per day (r = 0.8; p = 0.004). CONCLUSION Our findings suggest that persistent hypoxia gradually increases vagal tone with time, indicated by augmented bradycardia during apnea and progressively increased the incidence of arrhythmia at high altitude.
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Affiliation(s)
- Lindsey F Berthelsen
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, 1-059A Li Ka Shing Centre for Health Research Innovation, 8602-112 St, Edmonton, AB, T6G 2E1, Canada
| | - Sean van Diepen
- Faculty of Medicine and Dentistry, Department of Critical Care and Division of Cardiology, Department of Medicine, University of Alberta, Edmonton, AB, Canada
| | - Andrew R Steele
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, 1-059A Li Ka Shing Centre for Health Research Innovation, 8602-112 St, Edmonton, AB, T6G 2E1, Canada
| | - Emily R Vanden Berg
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, 1-059A Li Ka Shing Centre for Health Research Innovation, 8602-112 St, Edmonton, AB, T6G 2E1, Canada
| | - Jordan Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Scott Thrall
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, 1-059A Li Ka Shing Centre for Health Research Innovation, 8602-112 St, Edmonton, AB, T6G 2E1, Canada.,Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Alexandra Skalk
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Britta Byman
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Brandon Pentz
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada
| | - Nicholas G Jendzjowsky
- The Lundquist Institute for Biomedical Innovation at Harbor, UCLA Medical Center, Torrance, CA, USA
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, AB, Canada
| | - Craig D Steinback
- Neurovascular Health Lab, Faculty of Kinesiology, Sport, and Recreation, University of Alberta, 1-059A Li Ka Shing Centre for Health Research Innovation, 8602-112 St, Edmonton, AB, T6G 2E1, Canada.
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10
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Prodel E, Cavalcanti T, Rocha HNM, Gondim ML, Mira PAC, Fisher JP, Nobrega ACL. Sympathetic regulation of coronary circulation during handgrip exercise and isolated muscle metaboreflex activation in men. Exp Physiol 2021; 106:2400-2411. [PMID: 34719804 DOI: 10.1113/ep089954] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/29/2021] [Indexed: 01/10/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the role of β- and α-adrenergic receptors in the control of the coronary circulation during handgrip exercise and isolated muscle metaboreflex activation in humans? What is the main finding and its importance? β-Adrenergic receptor, but not α-adrenergic receptor, blockade significantly blunted the increases in coronary blood velocity observed during handgrip. Coronary blood velocity was unchanged from baseline during isolated muscle metaboreflex activation. This highlights the important role of β-adrenergic receptors in the coronary circulation during handgrip in humans, and the more limited involvement of the α-adrenergic receptors. ABSTRACT We sought to investigate the role of β- and α-adrenergic receptors in coronary circulation during static handgrip exercise and isolated muscle metaboreflex activation in humans. Seventeen healthy young men underwent two experimental sessions, consisting of 3 min of static handgrip exercise at a target force of 40% maximum voluntary force (not achieved for the full 3 min), and 3 min of metaboreflex activation (post-exercise ischaemia) in two conditions: (1) control and β-blockade (oral propranolol), and (2) control and α-blockade (oral prazosin). In both sessions, coronary blood velocity (CBV, echocardiography) was increased during handgrip (Δ8.0 ± 7.4 cm s-1 ) but unchanged with metaboreflex activation (Δ2.5 ± 3.2 cm s-1 ) under control conditions. β-Blockade abolished the increase in CBV during handgrip, while CBV was unchanged from control with α-blockade. Cardiac work, estimated from rate pressure product (RPP; systolic blood pressure multiplied by heart rate), increased during handgrip and metaboreflex in control conditions in both sessions. β-Blockade reduced RPP responses to handgrip and metaboreflex, whereas α-blockade increased RPP, but the responses to handgrip and metaboreflex were unchanged. CBV and RPP were only significantly correlated during handgrip under control (r = 0.71, P < 0.01) and β-blockade (r = 0.54, P = 0.03) conditions, and the slope of this relationship was unaltered with β-blockade. Collectively, these findings indicate that β-adrenergic receptors play the primary role to the increase of coronary circulation during handgrip exercise, but CBV is unchanged with metaboreflex activation, while α-adrenergic receptor stimulation seems to exert no effect in the control of the coronary circulation during handgrip exercise and isolated muscle metaboreflex activation in humans.
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Affiliation(s)
- Eliza Prodel
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil.,National Institute for Science & Technology - INCT, (In)activity & Exercise, Brazil
| | - Thiago Cavalcanti
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil.,National Institute for Science & Technology - INCT, (In)activity & Exercise, Brazil
| | - Helena N M Rocha
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil.,National Institute for Science & Technology - INCT, (In)activity & Exercise, Brazil
| | - Maitê L Gondim
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil.,National Institute for Science & Technology - INCT, (In)activity & Exercise, Brazil
| | - Pedro A C Mira
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil.,National Institute for Science & Technology - INCT, (In)activity & Exercise, Brazil
| | - James P Fisher
- Department of Physiology, University of Auckland, Auckland, New Zealand
| | - Antonio C L Nobrega
- Laboratory of Exercise Science, Department of Physiology and Pharmacology, Fluminense Federal University, Niteroi, Brazil.,National Institute for Science & Technology - INCT, (In)activity & Exercise, Brazil
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11
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Xu J, Zeng J, Yan Y, Xu F. Hypoxic Exercise Exacerbates Hypoxemia and Acute Mountain Sickness in Obesity: A Case Analysis. Int J Environ Res Public Health 2021; 18:9078. [PMID: 34501667 DOI: 10.3390/ijerph18179078] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 08/14/2021] [Accepted: 08/23/2021] [Indexed: 12/21/2022]
Abstract
Acute mountain sickness (AMS) is a common syndrome characterized by headache, dizziness, loss of appetite, weakness, and nausea. As a major public health issue, obesity has increased in high altitude urban residents and intermittent commuters to high altitudes. The present study investigated acute hypoxic exposure and hypoxic exercise on hypoxemia severity and AMS symptoms in a physically active obese man. In this case analysis, peripheral oxygen saturation (SpO2) was used to evaluate hypoxemia, heart rate (HR) and blood pressure (BP) were used to reflect the function of autonomic nervous system (ANS), and Lake Louise scoring (LLS) was used to assess AMS. The results showed that acute hypoxic exposure led to severe hypoxemia (SpO2 = 72%) and tachycardia (HRrest = 97 bpm), and acute hypoxic exercise exacerbated severe hypoxemia (SpO2 = 59%) and ANS dysfunction (HRpeak = 167 bpm, SBP/DBP = 210/97 mmHg). At the end of the 6-h acute hypoxic exposure, the case developed severe AMS (LLS = 10) symptoms of headache, gastrointestinal distress, cyanosis, vomiting, poor appetite, and fatigue. The findings of the case study suggest that high physical activity level appears did not show a reliable protective effect against severe hypoxemia, ANS dysfunction, and severe AMS symptoms in acute hypoxia exposure and hypoxia exercise.
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12
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Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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13
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Hofmann GC, Hasser EM, Kline DD. Unilateral vagotomy alters astrocyte and microglial morphology in the nucleus tractus solitarii of the rat. Am J Physiol Regul Integr Comp Physiol 2021; 320:R945-R959. [PMID: 33978480 PMCID: PMC8285617 DOI: 10.1152/ajpregu.00019.2021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 04/09/2021] [Accepted: 05/04/2021] [Indexed: 12/11/2022]
Abstract
The nucleus tractus solitarii (nTS) is the initial site of integration of sensory information from the cardiorespiratory system and contributes to reflex responses to hypoxia. Afferent fibers of the bilateral vagus nerves carry input from the heart, lungs, and other organs to the nTS where it is processed and modulated. Vagal afferents and nTS neurons are integrally associated with astrocytes and microglia that contribute to neuronal activity and influence cardiorespiratory control. We hypothesized that vagotomy would alter glial morphology and cardiorespiratory responses to hypoxia. Unilateral vagotomy (or sham surgery) was performed in rats. Prior to and seven days after surgery, baseline and hypoxic cardiorespiratory responses were monitored in conscious and anesthetized animals. The brainstem was sectioned and caudal, mid-area postrema (mid-AP), and rostral sections of the nTS were prepared for immunohistochemistry. Vagotomy increased immunoreactivity (-IR) of astrocytic glial fibrillary acidic protein (GFAP), specifically at mid-AP in the nTS. Similar results were found in the dorsal motor nucleus of the vagus (DMX). Vagotomy did not alter nTS astrocyte number, yet increased astrocyte branching and altered morphology. In addition, vagotomy both increased nTS microglia number and produced morphologic changes indicative of activation. Cardiorespiratory baseline parameters and hypoxic responses remained largely unchanged, but vagotomized animals displayed fewer augmented breaths (sighs) in response to hypoxia. Altogether, vagotomy alters nTS glial morphology, indicative of functional changes in astrocytes and microglia that may affect cardiorespiratory function in health and disease.
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Affiliation(s)
- Gabrielle C Hofmann
- Comparative Medicine, University of Missouri, Columbia, Missouri
- Area Pathobiology, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - Eileen M Hasser
- Area Pathobiology, University of Missouri, Columbia, Missouri
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
| | - David D Kline
- Area Pathobiology, University of Missouri, Columbia, Missouri
- Department of Biomedical Sciences, University of Missouri, Columbia, Missouri
- Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri
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14
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Fornasiero A, Zignoli A, Rakobowchuk M, Stella F, Savoldelli A, Skafidas S, Schena F, Pellegrini B, Mourot L. Post-exercise cardiac autonomic and cardiovascular responses to heart rate-matched and work rate-matched hypoxic exercise. Eur J Appl Physiol 2021; 121:2061-76. [PMID: 33811558 DOI: 10.1007/s00421-021-04678-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 03/28/2021] [Indexed: 12/30/2022]
Abstract
Purpose This study investigated the effect of performing hypoxic exercise at the same heart rate (HR) or work rate (WR) as normoxic exercise on post-exercise autonomic and cardiovascular responses. Methods Thirteen men performed three interval-type exercise sessions (5 × 5-min; 1-min recovery): normoxic exercise at 80% of the WR at the first ventilatory threshold (N), hypoxic exercise (FiO2 = 14.2%) at the same WR as N (H-WR) and hypoxic exercise at the same HR as N (H-HR). Autonomic and cardiovascular assessments were conducted before and after exercise, both at rest and during active squat–stand manoeuvres (SS). Results Compared to N, H-WR elicited a higher HR response (≈ 83% vs ≈ 75%HRmax, p < 0.001) and H-HR a reduced exercise WR (− 21.1 ± 9.3%, p < 0.001). Cardiac parasympathetic indices were reduced 15 min after exercise and recovered within 60 min in N and H-HR, but not after H-WR (p < 0.05). H-WR altered cardiac baroreflex sensitivity (cBRS) both at rest and during SS (specifically in the control of blood pressure fall during standing phases) in the first 60 min after the exercise bout (p < 0.05). Post-exercise hypotension (PEH) did not occur in H-HR (p > 0.05) but lasted longer in H-WR than in N (p < 0.05). Conclusions Moderate HR-matched hypoxic exercise mimicked post-exercise autonomic responses of normoxic exercise without resulting in significant PEH. This may relate to the reduced WR and the limited associated mechanical/metabolic strain. Conversely, WR-matched hypoxic exercise impacted upon post-exercise autonomic and cardiovascular responses, delaying cardiac autonomic recovery, temporarily decreasing cBRS and evoking prolonged PEH. Supplementary Information The online version contains supplementary material available at 10.1007/s00421-021-04678-5.
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15
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Gatterer H, Rauch S, Regli IB, Woyke S, Schlittler M, Turner R, Strapazzon G, Brugger H, Goetze JP, Feraille E, Siebenmann C. Plasma volume contraction reduces atrial natriuretic peptide after four days of hypobaric hypoxia exposure. Am J Physiol Regul Integr Comp Physiol 2021; 320:R526-R531. [PMID: 33533684 DOI: 10.1152/ajpregu.00313.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether low arterial oxygen tension ([Formula: see text]) or hypoxia-induced plasma volume (PV) contraction, which reduces central blood volume (BV) and atrial distension, explain reduction in circulating atrial natriuretic peptide (ANP) after prolonged hypoxic exposure. Ten healthy males were exposed for 4 days to hypobaric hypoxia corresponding to an altitude of 3,500 m. PV changes were determined by carbon monoxide rebreathing. Venous plasma concentrations of midregional proANP (MR-proANP) were measured before and at the end of the exposure. At the latter time point, the measurement was repeated after 1) restoration of [Formula: see text] by breathing a hyperoxic gas mixture for 30 min and 2) restoration of BV by fluid infusion. Correspondingly, left ventricular end-diastolic volume (LVEDV), left atrial area (LAA), and right atrial area (RAA) were determined by ultrasound before exposure and both before and after fluid infusion at the end of the exposure. Hypoxic exposure reduced MR-proANP from 37.9 ± 18.5 to 24.5 ± 10.3 pmol/L (P = 0.034), LVEDV from 107.4 ± 33.5 to 91.6 ± 26.3 mL (P = 0.005), LAA from 15.8 ± 4.9 to 13.3 ± 4.2 cm2 (P = 0.007), and RAA from 16.2 ± 3.1 to 14.3 ± 3.5 cm2 (P = 0.001). Hyperoxic breathing did not affect MR-proANP (24.8 ± 12.3 pmol/L, P = 0.890). Conversely, fluid infusion restored LVEDV, LAA, and RAA to near-baseline values (108.0 ± 29.3 mL, 17.2 ± 5.7 cm2, and 17.2 ± 3.1 cm2, respectively, P > 0.05 vs. baseline) and increased MR-proANP to 29.5 ± 13.3 pmol/L (P = 0.010 vs. preinfusion and P = 0.182 vs. baseline). These findings support that ANP reduction in hypoxia is at least partially attributed to plasma volume contraction, whereas reduced [Formula: see text] does not seem to contribute.
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Affiliation(s)
- Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Simon Rauch
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesia and Intensive Care Medicine, "F. Tappeiner" Hospital, Merano, Italy
| | - Ivo B Regli
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesia and Intensive Care Medicine, "F. Tappeiner" Hospital, Merano, Italy
| | - Simon Woyke
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy.,Department of Anesthesiology and Intensive Care Medicine, Medical University of Innsbruck, Innsbruck, Austria
| | - Maja Schlittler
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Rachel Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giacomo Strapazzon
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hermann Brugger
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Jens P Goetze
- Department of Clinical Biochemistry, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Eric Feraille
- National Center of Competence in Research Kidney Control of Homeostasis (Kidney.CH), Zurich, Switzerland.,Department of Cellular Physiology and Metabolism, University of Geneva, University Medical Center, Geneva, Switzerland
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16
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Arce-Álvarez A, Veliz C, Vazquez-Muñoz M, von Igel M, Alvares C, Ramirez-Campillo R, Izquierdo M, Millet GP, Del Rio R, Andrade DC. Hypoxic Respiratory Chemoreflex Control in Young Trained Swimmers. Front Physiol 2021; 12:632603. [PMID: 33716781 PMCID: PMC7953139 DOI: 10.3389/fphys.2021.632603] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 02/08/2021] [Indexed: 11/27/2022] Open
Abstract
During an apnea, changes in PaO2 activate peripheral chemoreceptors to increase respiratory drive. Athletes with continuous apnea, such as breath-hold divers, have shown a decrease in hypoxic ventilatory response (HVR), which could explain the long apnea times; however, this has not been studied in swimmers. We hypothesize that the long periods of voluntary apnea in swimmers is related to a decreased HVR. Therefore, we sought to determine the HVR and cardiovascular adjustments during a maximum voluntary apnea in young-trained swimmers. In fifteen trained swimmers and twenty-seven controls we studied minute ventilation (VE), arterial saturation (SpO2), heart rate (HR), and autonomic response [through heart rate variability (HRV) analysis], during acute chemoreflex activation (five inhalations of pure N2) and maximum voluntary apnea test. In apnea tests, the maximum voluntary apnea time and the end-apnea HR were higher in swimmers than in controls (p < 0.05), as well as a higher low frequency component of HRV (p < 0.05), than controls. Swimmers showed lower HVR than controls (p < 0.01) without differences in cardiac hypoxic response (CHR). We conclude that swimmers had a reduced HVR response and greater maximal voluntary apnea duration, probably due to decreased HVR.
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Affiliation(s)
- Alexis Arce-Álvarez
- Escuela de Kinesiología, Facultad de Salud, Universidad Católica Silva Henríquez, Santiago, Chile
| | - Carlos Veliz
- Centro de Investigación en Fisiología del Ejercicio, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Manuel Vazquez-Muñoz
- Navarrabiomed, Complejo Hospitalario de Navarra (CHN), Universidad Pública de Navarra, IdiSNA, Pamplona, Spain.,Unidad de Estadística, Departamento de Calidad, Clínica Santa María, Santiago, Chile
| | - Magdalena von Igel
- Centro de Investigación en Fisiología del Ejercicio, Facultad de Ciencias, Universidad Mayor, Santiago, Chile
| | - Cristian Alvares
- Laboratory of Human Performance, Quality of Life and Wellness Research Group, Department of Physical Activity Sciences, Universidad de Los Lagos, Osorno, Chile
| | - Rodrigo Ramirez-Campillo
- Centro de Investigación en Fisiología del Ejercicio, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.,Laboratory of Human Performance, Quality of Life and Wellness Research Group, Department of Physical Activity Sciences, Universidad de Los Lagos, Osorno, Chile
| | - Mikel Izquierdo
- Navarrabiomed, Complejo Hospitalario de Navarra (CHN), Universidad Pública de Navarra, IdiSNA, Pamplona, Spain
| | - Gregoire P Millet
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Envejecimiento y Regeneración (CARE), Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Excelencia en Biomedicina de Magallanes (CEBIMA), Universidad de Magallanes, Punta Arenas, Chile
| | - David C Andrade
- Centro de Investigación en Fisiología del Ejercicio, Facultad de Ciencias, Universidad Mayor, Santiago, Chile.,Laboratory of Cardiorespiratory Control, Department of Physiology, Pontificia Universidad Católica de Chile, Santiago, Chile.,Centro de Fisiología y Medicina de Altura, Facultad de Ciencias de la Salud, Universidad de Antofagasta, Antofagasta, Chile
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17
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Neuls F, Krejci J, Jakubec A, Botek M, Valenta M. Vagal Threshold Determination during Incremental Stepwise Exercise in Normoxia and Normobaric Hypoxia. Int J Environ Res Public Health 2020; 17:E7579. [PMID: 33086469 DOI: 10.3390/ijerph17207579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/01/2020] [Accepted: 10/14/2020] [Indexed: 11/20/2022]
Abstract
This study focuses on the determination of the vagal threshold (Tva) during exercise with increasing intensity in normoxia and normobaric hypoxia. The experimental protocol was performed by 28 healthy men aged 20 to 30 years. It included three stages of exercise on a bicycle ergometer with a fraction of inspired oxygen (FiO2) 20.9% (normoxia), 17.3% (simulated altitude ~1500 m), and 15.3% (~2500 m) at intensity associated with 20% to 70% of the maximal heart rate reserve (MHRR) set in normoxia. Tva level in normoxia was determined at exercise intensity corresponding with (M ± SD) 45.0 ± 5.6% of MHRR. Power output at Tva (POth), representing threshold exercise intensity, decreased with increasing degree of hypoxia (normoxia: 114 ± 29 W; FiO2 = 17.3%: 110 ± 27 W; FiO2 = 15.3%: 96 ± 32 W). Significant changes in POth were observed with FiO2 = 15.3% compared to normoxia (p = 0.007) and FiO2 = 17.3% (p = 0.001). Consequentially, normoxic %MHRR adjusted for hypoxia with FiO2 = 15.3% was reduced to 39.9 ± 5.5%. Considering the convenient altitude for exercise in hypoxia, POth did not differ excessively between normoxic conditions and the simulated altitude of ~1500 m, while more substantial decline of POth occurred at the simulated altitude of ~2500 m compared to the other two conditions.
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18
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Fornasiero A, Savoldelli A, Stella F, Callovini A, Bortolan L, Zignoli A, Low DA, Mourot L, Schena F, Pellegrini B. Shortening Work-Rest Durations Reduces Physiological and Perceptual Load During Uphill Walking in Simulated Cold High-Altitude Conditions. High Alt Med Biol 2020; 21:249-257. [PMID: 32412801 DOI: 10.1089/ham.2019.0136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Fornasiero, Alessandro, Aldo Savoldelli, Federico Stella, Alexa Callovini, Lorenzo Bortolan, Andrea Zignoli, David A. Low, Laurent Mourot, Federico Schena, and Barbara Pellegrini. Shortening work-rest durations reduces physiological and perceptual load during uphill walking in simulated cold high-altitude conditions. High Alt Med Biol. 21:249-257, 2020. Background: We investigated the effects of two different work-rest durations on the physiological and perceptual responses to a simulated mountain hike in a cold hypoxic environment. Materials and Methods: Twelve healthy nonacclimatized active men (age 31.3 ± 5.3 years, body mass index 22.4 ± 1.5 kg/m2) completed a 80-minute work-matched intermittent exercise on a motorized treadmill (25% incline, fixed self-selected speed), in a simulated mountain environment (-25°C, FiO2 = 11%, ≈5000 m a.s.l.), wearing extreme cold weather gear, once with short (20 × 3 minutes walking with 1 minute rest; SHORT) and once with long (10 × 6 minutes walking with 2 minutes rest; LONG) work-rest durations. Heart rate (HR), pulse oxygen saturation (SpO2), rate of perceived exertion (RPE), and thermal sensation (TS) were assessed throughout the exercise protocols. Cardiac autonomic modulation was assessed before (PRE) and after exercise (POST) in supine position, as well as during standing resting periods by means of HR recovery (HRR) assessment. Results: SpO2 and TS were similar (p > 0.05) in SHORT and LONG protocols. HR and RPE were increased, and HRR reduced during LONG compared to SHORT (p < 0.05). Parasympathetic activity indices were reduced at POST after both protocols (p < 0.05), but to a lesser extent after SHORT (p < 0.05). Conclusions: Reduced work-rest durations are associated with improved perceptual responses and less perturbation of cardiac autonomic balance, compared to longer work-rest durations. Shorter exercise periods from more frequent breaks during hikes at high altitude may represent a valid strategy to limit the impact of exercise under extreme environmental conditions.
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Affiliation(s)
- Alessandro Fornasiero
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Aldo Savoldelli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Federico Stella
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Alexa Callovini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy
| | - Lorenzo Bortolan
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Andrea Zignoli
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Industrial Engineering, University of Trento, Trento, Italy
| | - David A Low
- Research Institute for Sport and Exercise Sciences (RISES), Liverpool John Moores University, Liverpool, United Kingdom
| | - Laurent Mourot
- Laboratory of Prognostic Markers and Regulatory Factors of Cardiovascular Diseases and Exercise Performance, Health, Innovation Platform (EA 3920), University of Bourgogne Franche-Comté, Besançon, France.,Tomsk Polytechnic University, Tomsk, Russia
| | - Federico Schena
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
| | - Barbara Pellegrini
- CeRiSM, Sport Mountain and Health Research Centre, University of Verona, Rovereto, Italy.,Department of Neurosciences, Biomedicine and Movement Sciences, University of Verona, Verona, Italy
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19
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Abstract
The carotid body has emerged as a therapeutic target for cardio-respiratory-metabolic diseases. With the expansive functions of the chemoreflex, we sought mechanisms to explain differential control of individual responses. We purport a remarkable correlation between phenotype of a chemosensory unit (glomus cell-sensory afferent) with a distinct component of the reflex response. This logic could permit differential modulation of distinct chemoreflex responses, a strategy ideal for therapeutic exploitation.
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Affiliation(s)
- Tymoteusz Zera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw , Warsaw , Poland
| | - Davi J A Moraes
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo , São Paulo , Brazil
| | - Melina P da Silva
- Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo , São Paulo , Brazil
| | - James P Fisher
- Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland , Auckland , New Zealand
| | - Julian F R Paton
- Department of Physiology, Faculty of Medical & Health Sciences, University of Auckland , Auckland , New Zealand
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20
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Hermand E, Pichon A, Lhuissier FJ, Richalet JP. Low-frequency ventilatory oscillations in hypoxia are a major contributor to the low-frequency component of heart rate variability. Eur J Appl Physiol 2019; 119:1769-1777. [PMID: 31154522 DOI: 10.1007/s00421-019-04166-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Revised: 04/19/2019] [Accepted: 05/23/2019] [Indexed: 12/23/2022]
Abstract
PURPOSE Heart rate variability (HRV) may be influenced by several factors, such as environment (hypoxia, hyperoxia, hypercapnia) or physiological demand (exercise). In this retrospective study, we tested the hypothesis that inter-beat (RR) intervals in healthy subjects exercising under various environmental stresses exhibit oscillations at the same frequency than ventilatory oscillations. METHODS Spectra from RR intervals and ventilation ([Formula: see text]E) were collected from 37 healthy young male subjects who participated in 5 previous studies focused on ventilatory oscillations (or periodic breathing) during exercise in hypoxia, hyperoxia and hypercapnia. Bland and Altman test and multivariate regressions were then performed to compare respective frequencies and changes in peak powers of the two signals. RESULTS Fast Fourier analysis of RR and [Formula: see text]E signals showed that RR was oscillating at the same frequency than periodic breathing, i.e., ~ 0.09 Hz (11 s). During exercise, in these various conditions, the difference between minimum and maximum HRV peak power was positively correlated to the same change in ventilation peak power (P < 0.05). Low-frequency (LF) peak power was correlated to tidal volume (P < 0.01) and breathing frequency (P < 0.001). CONCLUSIONS This study suggests that low-frequency ventilatory oscillations in hypoxia are a major contributor to the LF band power of heart rate variability. CLINICAL TRIAL REG. NO.: NCT02201875.
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Affiliation(s)
- Eric Hermand
- Laboratoire HAVAE 'Handicap, Activité, Vieillissement, Autonomie, Environnement', E6310, Université de Limoges, Faculté Des Sciences Et Techniques, 123 avenue Albert Thomas, 87060, Limoges Cedex, France.
- Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon", E2363, Université Paris 13, Bobigny, France.
| | - Aurélien Pichon
- Laboratoire MOVE, Université de Poitiers, E6314, Poitiers, France
| | - François J Lhuissier
- Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon", E2363, Université Paris 13, Bobigny, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Avicenne, Service de Physiologie, Explorations Fonctionnelles Et Médecine du Sport, 93009, Bobigny, France
| | - Jean-Paul Richalet
- Sorbonne Paris Cité, Laboratoire "Hypoxie & Poumon", E2363, Université Paris 13, Bobigny, France
- Département Médical, Institut National de L'Expertise Et de La Performance, 75012, Paris, France
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