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Hilz MJ, Wang R, Marthol H, Liu M, Tillmann A, Riss S, Hauck P, Hösl KM, Wasmeier G, Stemper B, Köhrmann M. Partial pharmacologic blockade shows sympathetic connection between blood pressure and cerebral blood flow velocity fluctuations. J Neurol Sci 2016; 365:181-7. [PMID: 27206903 DOI: 10.1016/j.jns.2016.04.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Revised: 03/24/2016] [Accepted: 04/07/2016] [Indexed: 11/18/2022]
Abstract
Cerebral autoregulation (CA) dampens transfer of blood pressure (BP)-fluctuations onto cerebral blood flow velocity (CBFV). Thus, CBFV-oscillations precede BP-oscillations. The phase angle (PA) between sympathetically mediated low-frequency (LF: 0.03-0.15Hz) BP- and CBFV-oscillations is a measure of CA quality. To evaluate whether PA depends on sympathetic modulation, we assessed PA-changes upon sympathetic stimulation with and without pharmacologic sympathetic blockade. In 10 healthy, young men, we monitored mean BP and CBFV before and during 120-second cold pressor stimulation (CPS) of one foot (0°C ice-water). We calculated mean values, standard deviations and sympathetic LF-powers of all signals, and PAs between LF-BP- and LF-CBFV-oscillations. We repeated measurements after ingestion of the adrenoceptor-blocker carvedilol (25mg). We compared parameters before and during CPS, without and after carvedilol (analysis of variance, post-hoc t-tests, significance: p<0.05). Without carvedilol, CPS increased BP, CBFV, BP-LF- and CBFV-LF-powers, and shortened PA. Carvedilol decreased resting BP, CBFV, BP-LF- and CBFV-LF-powers, while PAs remained unchanged. During CPS, BPs, CBFVs, BP-LF- and CBFV-LF-powers were lower, while PAs were longer with than without carvedilol. With carvedilol, CPS no longer shortened resting PA. Sympathetic activation shortens PA. Partial adrenoceptor blockade abolishes this PA-shortening. Thus, PA-measurements provide a subtle marker of sympathetic influences on CA and might refine CA evaluation.
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Affiliation(s)
- Max J Hilz
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Ruihao Wang
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Harald Marthol
- Department of Psychiatry, Addiction, Psychotherapy and Psychosomatics, Klinikum am Europakanal, Am Europakanal 71, 91056 Erlangen, Germany.
| | - Mao Liu
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Alexandra Tillmann
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Stephan Riss
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Paulina Hauck
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
| | - Katharina M Hösl
- Department of Psychiatry and Psychotherapy, Paracelsus Medical University Nuremberg, Prof.-Ernst-Nathan-Strasse 1, 90419 Nuremberg, Germany.
| | - Gerald Wasmeier
- Department of Cardiology, Klinik Neustadt a. d. Aisch, Paracelsusstraße 30-36, 91413 Neustadt a. d. Aisch, Germany.
| | - Brigitte Stemper
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany; Bayer HealthCare, Bayer Pharma AG, Global Development Specialty Medicine, Müllerstr. 178, Building P300, Room 239, 13353 Berlin, Germany.
| | - Martin Köhrmann
- Department of Neurology, University of Erlangen-Nuremberg, Schwabachanlage 6, D-91054 Erlangen, Germany.
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Hilz MJ, Aurnhammer F, Flanagan SR, Intravooth T, Wang R, Hösl KM, Pauli E, Koehn J. Eyeball Pressure Stimulation Unveils Subtle Autonomic Cardiovascular Dysfunction in Persons with a History of Mild Traumatic Brain Injury. J Neurotrauma 2015; 32:1796-804. [DOI: 10.1089/neu.2014.3842] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Max J. Hilz
- Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Felix Aurnhammer
- Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Steven R. Flanagan
- Department of Rehabilitation Medicine, New York University School of Medicine, New York, New York
| | - Tassanai Intravooth
- Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Ruihao Wang
- Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Katharina M. Hösl
- Department of Psychiatry, Addiction Psychiatry, Psychotherapy, and Psychosomatic Medicine, Klinikum am Europakanal Erlangen, Erlangen, Germany
| | - Elisabeth Pauli
- Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany
| | - Julia Koehn
- Department of Neurology, University of Erlangen-Nuremberg, Erlangen, Germany
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Vianna LC, Deo SH, Jensen AK, Holwerda SW, Zimmerman MC, Fadel PJ. Impaired dynamic cerebral autoregulation at rest and during isometric exercise in type 2 diabetes patients. Am J Physiol Heart Circ Physiol 2015; 308:H681-7. [PMID: 25599569 DOI: 10.1152/ajpheart.00343.2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 01/15/2015] [Indexed: 12/21/2022]
Abstract
Type 2 diabetes mellitus patients (T2D) have elevated risk of stroke, suggesting that cerebrovascular function is impaired. Herein, we examined dynamic cerebral autoregulation (CA) at rest and during exercise in T2D patients and determined whether underlying systemic oxidative stress is associated with impairments in CA. Middle cerebral artery blood velocity and arterial blood pressure (BP) were measured at rest and during 2-min bouts of low- and high-intensity isometric handgrip performed at 20% and 40% maximum voluntary contraction, respectively, in seven normotensive and eight hypertensive T2D patients and eight healthy controls. Dynamic CA was estimated using the rate of regulation (RoR). Total reactive oxygen species (ROS) and superoxide levels were measured at rest. There were no differences in RoR at rest or during exercise between normotensive and hypertensive T2D patients. However, when compared with controls, T2D patients exhibited lower RoR at rest and during low-intensity handgrip indicating impaired dynamic CA. Moreover, the RoR was further reduced by 29 ± 4% during high-intensity handgrip in T2D patients (0.307 ± 0.012/s rest vs. 0.220 ± 0.014/s high intensity; P < 0.01), although well maintained in controls. T2D patients demonstrated greater baseline total ROS and superoxide compared with controls, both of which were negatively related to RoR during handgrip (e.g., total ROS: r = -0.71, P < 0.05; 40% maximum voluntary contraction). Collectively, these data demonstrate impaired dynamic CA at rest and during isometric handgrip in T2D patients, which may be, in part, related to greater underlying systemic oxidative stress. Additionally, dynamic CA is blunted further with high intensity isometric contractions potentially placing T2D patients at greater risk for cerebral events during such activities.
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Affiliation(s)
- Lauro C Vianna
- Faculty of Physical Education, University of Brasília, DF, Brazil; Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Shekhar H Deo
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Areum K Jensen
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Seth W Holwerda
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri
| | - Matthew C Zimmerman
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center, Omaha, Nebraska
| | - Paul J Fadel
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, Missouri; Dalton Cardiovascular Research Center, University of Missouri, Columbia, Missouri; and
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Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow. Med Eng Phys 2014; 36:563-75. [DOI: 10.1016/j.medengphy.2014.02.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2013] [Revised: 01/31/2014] [Accepted: 02/03/2014] [Indexed: 12/21/2022]
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Huq R, Philbey CE, Mistri AK, Panerai RB, Robinson TG. Dynamic cerebral autoregulation assessed by respiratory manoeuvres in non-insulin-treated Type 2 diabetes mellitus. Diabet Med 2012; 29:609-13. [PMID: 22004530 DOI: 10.1111/j.1464-5491.2011.03497.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIMS This study investigated dynamic cerebral autoregulation in Type 2 diabetes, where dynamic cerebral autoregulation may be impaired as a consequence of microvascular changes and/or autonomic neuropathy. METHODS Eleven healthy control subjects and 11 age- and sex-matched patients with Type 2 diabetes controlled with lifestyle modifications or oral anti-diabetes treatment were recruited. Dynamic cerebral autoregulation was calculated by the autoregressive moving average autoregulatory index from a continuous blood pressure and R-R interval (time between each ventricular systole) recording. End-tidal carbon dioxide was also monitored and changes in response to breath holding and hyperventilation as a metabolic stimulus were measured. RESULTS No significant differences were seen in cerebral blood flow velocity at baseline, or in response to breath holding between people with diabetes and control subjects, although the cerebral blood flow velocity response associated with hyperventilation was significantly reduced in the diabetes group. No significant differences in dynamic cerebral autoregulation were seen at baseline or in response to respiratory manoeuvres between the groups. CONCLUSIONS Dynamic cerebral autoregulation is not impaired in patients with Type 2 diabetes, although a small difference could not be excluded as the study was only powered to detect an autoregulatory index difference > 2 units. Further study in a larger population with a spectrum of disease severity may reveal clinically important differences.
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Affiliation(s)
- R Huq
- Ageing and Stroke Medicine Medical Physics Groups, Department of Cardiovascular Sciences, University of Leicester, Leicester, UK
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Alveolar gas exchange and tissue deoxygenation during exercise in type 1 diabetes patients and healthy controls. Respir Physiol Neurobiol 2012; 181:267-76. [PMID: 22538274 DOI: 10.1016/j.resp.2012.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Revised: 03/16/2012] [Accepted: 04/06/2012] [Indexed: 11/22/2022]
Abstract
We used near-infrared spectroscopy to investigate whether leg and arm skeletal muscle and cerebral deoxygenation differ during incremental cycling exercise in men with type 1 diabetes (T1D, n=10, mean±SD age 33±7 years) and healthy control men (matched by age, anthrometry, and self-reported physical activity, CON, n=10, 32±7 years) to seek an explanation for lower aerobic capacity (˙VO2peak) often reported in T1D. T1D had lower ˙VO2peak (35±4mlkg(-1)min(-1) vs. 43±8mlkg(-1)min(-1), P<0.01) and peak work rate (219±33W vs. 290±44W, P<0.001) than CON. Leg muscle deoxygenation (↑ [deoxyhemoglobin]; ↓ tissue saturation index) was greater in T1D than CON at a given absolute submaximal work rate, but not at peak exercise, while arm muscle and cerebral deoxygenation were similar. Thus, in T1D compared with CON, faster leg muscle deoxygenation suggests limited circulatory ability to increase O(2) delivery as a plausible explanation for lower ˙VO2peak and earlier fatigue in T1D.
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Oscillations in cerebral blood flow and cortical oxygenation in Alzheimer's disease. Neurobiol Aging 2011; 33:428.e21-31. [PMID: 21208686 DOI: 10.1016/j.neurobiolaging.2010.11.016] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 09/08/2010] [Accepted: 11/11/2010] [Indexed: 11/22/2022]
Abstract
In Alzheimer's disease (AD) cerebrovascular function is at risk. Transcranial Doppler, near-infrared spectroscopy, and photoplethysmography are noninvasive methods to continuously measure changes in cerebral blood flow velocity (CBFV), cerebral cortical oxygenated hemoglobin (O(2)Hb), and blood pressure (BP). In 21 patients with mild to moderate AD and 20 age-matched controls, we investigated how oscillations in cerebral blood flow velocity (CBFV) and O(2)Hb are associated with spontaneous and induced oscillations in blood pressure (BP) at the very low (VLF = 0.05 Hz) and low frequencies (LF = 0.1 Hz). We applied spectral and transfer function analysis to quantify dynamic cerebral autoregulation and brain tissue oxygenation. In AD, cerebrovascular resistance was substantially higher (34%, AD vs. control: Δ = 0.69 (0.25) mm Hg/cm/second, p = 0.012) and the transmission of very low frequency (VLF) cerebral blood flow (CBF) oscillations into O(2)Hb differed, with increased phase lag and gain (Δ phase 0.32 [0.15] rad; Δ gain 0.049 [0.014] μmol/cm/second, p both < 0.05). The altered transfer of CBF to cortical oxygenation in AD indicates that properties of the cerebral microvasculature are changed in this disease.
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Nasr N, Czosnyka M, Arevalo F, Hanaire H, Guidolin B, Larrue V. Autonomic neuropathy is associated with impairment of dynamic cerebral autoregulation in type 1 diabetes. Auton Neurosci 2010; 160:59-63. [PMID: 21036672 DOI: 10.1016/j.autneu.2010.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/07/2010] [Accepted: 10/04/2010] [Indexed: 11/30/2022]
Abstract
HYPOTHESIS The mechanisms underlying impairment of dynamic cerebral autoregulation in diabetes are not well known. Cardiovascular autonomic neuropathy (CAN) could contribute to dynamic cerebral autoregulation impairment. In this study, we assessed the association between CAN and impairment of dynamic cerebral autoregulation in patients with type 1 diabetes. METHODS We evaluated dynamic cerebral autoregulation (DCA) in patients with type 1 diabetes and no history of cerebrovascular disease. DCA was assessed with transcranial Doppler using the correlation coefficient index Mx method. Mx was calculated from slow changes in mean cerebral blood flow velocity and mean arterial blood pressure. Increase in Mx indicates weaker DCA, with a threshold for impaired DCA above 0.3. Moderate CAN was defined as reduced heart rate variability (HRV) on the following tests: deep controlled breathing, Valsalva maneuver or initiation of active standing. Severe CAN was defined as reduced HRV associated with orthostatic hypotension. RESULTS 60 patients were included (M/F: 33/27; mean age ± SD: 46 years ± 11.5). 23 patients had moderate CAN and 15 patients severe CAN. DCA was impaired in 37 patients. CAN was associated with impaired DCA (p = 0.005). Impairment of DCA was more pronounced in patients with severe CAN (p = 0.019). Glycosylated haemoglobin (HbA1c) was associated with impaired DCA in univariate analysis (p = 0.05). In multivariate analysis, only CAN was associated with impaired DCA (p = 0.007) whereas HbA1c was not (p = 0.161). CONCLUSIONS CAN was associated with impaired DCA in type 1 diabetes. The magnitude of DCA impairment increased with the severity of CAN.
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Affiliation(s)
- N Nasr
- Service de Neurologie Vasculaire, Hôpital Rangueil, Toulouse, INSERM U, France.
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