TY - JOUR
T1 - The influence of the carotid baroreflex on dynamic regulation of cerebral blood flow and cerebral tissue oxygenation in humans at rest and during exercise
AU - Purkayastha, Sushmita
AU - Maffuid, Kaitlyn
AU - Zhu, Xiaojie
AU - Zhang, Rong
AU - Raven, Peter B.
N1 - Funding Information:
Funding This study was supported in part by funds provided by the Cardiovascular Research Institute and the Department of Integrative Physiology at the University of North Texas Health Science Center at Fort Worth, TX. The authors also wish to thank the subjects for volunteering to undertake the study.
Publisher Copyright:
© 2018, Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2018/5/1
Y1 - 2018/5/1
N2 - 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. 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 (ScO2) in the low-frequency range (0.07–0.20 Hz) was estimated to examine NP stimuli responses. 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 ScO2 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 ScO2 (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). 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.
AB - 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. 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 (ScO2) in the low-frequency range (0.07–0.20 Hz) was estimated to examine NP stimuli responses. 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 ScO2 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 ScO2 (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). 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.
KW - Cerebral blood vessels
KW - Cerebral tissue oxygenation
KW - Dynamic exercise
KW - Power spectral density
KW - Sympathetic activity
KW - Transfer function gain
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U2 - 10.1007/s00421-018-3831-1
DO - 10.1007/s00421-018-3831-1
M3 - Article
C2 - 29497836
AN - SCOPUS:85045057746
SN - 1439-6319
VL - 118
SP - 959
EP - 969
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
IS - 5
ER -