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The influence of the carotid baroreflex on dynamic regulation of cerebral blood flow and cerebral tissue oxygenation in humans at rest and during exercise.
- Source :
-
European journal of applied physiology [Eur J Appl Physiol] 2018 May; Vol. 118 (5), pp. 959-969. Date of Electronic Publication: 2018 Mar 01. - Publication Year :
- 2018
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Abstract
- Purpose: This preliminary study tested the hypothesis that the carotid baroreflex (CBR) mediated sympathoexcitation regulates cerebral blood flow (CBF) at rest and during dynamic exercise.<br />Methods: In seven healthy subjects (26 ± 1 years), oscillatory neck pressure (NP) stimuli of + 40 mmHg were applied to the carotid baroreceptors at a pre-determined frequency of 0.1 Hz at rest, low (10 ± 1W), and heavy (30 ± 3W) exercise workloads (WLs) without (control) and with α - 1 adrenoreceptor blockade (prazosin). Spectral power analysis of the mean arterial blood pressure (MAP), mean middle cerebral artery blood velocity (MCAV), and cerebral tissue oxygenation index (ScO <subscript>2</subscript> ) in the low-frequency range (0.07-0.20 Hz) was estimated to examine NP stimuli responses.<br />Results: From rest to heavy exercise, WLs resulted in a greater than three-fold increase in MCAV power (42 ± 23.8-145.2 ± 78, p < 0.01) and an almost three-fold increase in ScO <subscript>2</subscript> power (0.51 ± 0.3-1.53 ± 0.8, p = 0.01), even though there were no changes in MAP power (from 24.5 ± 21 to 22.9 ± 11.9) with NP stimuli. With prazosin, the overall MAP (p = 0.0017), MCAV (p = 0.019), and ScO <subscript>2</subscript> (p = 0.049) power was blunted regardless of the exercise conditions. Prazosin blockade resulted in increases in the Tf gain index between MAP and MCAV compared to the control (p = 0.03).<br />Conclusion: CBR-mediated changes in sympathetic activity contribute to dynamic regulation of the cerebral vasculature and CBF at rest and during dynamic exercise in humans.
Details
- Language :
- English
- ISSN :
- 1439-6327
- Volume :
- 118
- Issue :
- 5
- Database :
- MEDLINE
- Journal :
- European journal of applied physiology
- Publication Type :
- Academic Journal
- Accession number :
- 29497836
- Full Text :
- https://doi.org/10.1007/s00421-018-3831-1