Staff View: Neurovascular coupling is not influenced by lower body negative pressure in humans

Neurovascular coupling is not influenced by lower body negative pressure in humans

Cerebral blood flow is tightly coupled with local neuronal activation and metabolism, i.e., neurovascular coupling (NVC). Studies suggest a role of sympathetic nervous system in the regulation of cerebral blood flow. However, this is controversial, and the sympathetic regulation of NVC in humans rem...

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Main Authors:	Samora, Milena, Vianna, Lauro Casqueiro, Carmo, Jake C., Macedo, Victor, Dawes, Matthew, Phillips, Aaron A., Paton, Julian F. R., Fisher, James P.
Format:	Artigo
Language:	Inglês
Published:	American Physiological Society 2021
Subjects:	Circulação cerebral Acoplamento neurovascular Sistema nervoso simpático
Online Access:	https://repositorio.unb.br/handle/10482/40206 https://doi.org/10.1152/ajpheart.00076.2020 https://orcid.org/0000-0001-6348-1786 https://orcid.org/0000-0002-5747-0295 https://orcid.org/0000-0001-7851-9222
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spelling	ir-10482-402062021-03-10T18:21:40Z Neurovascular coupling is not influenced by lower body negative pressure in humans Samora, Milena Vianna, Lauro Casqueiro Carmo, Jake C. Macedo, Victor Dawes, Matthew Phillips, Aaron A. Paton, Julian F. R. Fisher, James P. Circulação cerebral Acoplamento neurovascular Sistema nervoso simpático Cerebral blood flow is tightly coupled with local neuronal activation and metabolism, i.e., neurovascular coupling (NVC). Studies suggest a role of sympathetic nervous system in the regulation of cerebral blood flow. However, this is controversial, and the sympathetic regulation of NVC in humans remains unclear. Since impaired NVC has been identified in several chronic diseases associated with a heightened sympathetic activity, we aimed to determine whether reflex-mediated sympathetic activation via lower body negative pressure (LBNP) attenuates NVC in humans. NVC was assessed using a visual stimulation protocol (5 cycles of 30 s eyes closed and 30 s of reading) in 11 healthy participants (aged 24 ± 3 yr). NVC assessments were made under control conditions and during LBNP at -20 and -40 mmHg. Posterior (PCA) and middle (MCA) cerebral artery mean blood velocity (Vmean) and vertebral artery blood flow (VAflow) were simultaneously determined with cardiorespiratory variables. Under control conditions, the visual stimulation evoked a robust increase in PCAVmean (∆18.0 ± 4.5%), a moderate rise in VAflow (∆9.6 ± 4.3%), and a modest increase in MCAVmean (∆3.0 ± 1.9%). The magnitude of NVC response was not affected by mild-to-moderate LBNP (all P > 0.05 for repeated-measures ANOVA). Given the small change that occurred in partial pressure of end-tidal CO2 during LBNP, this hypocapnia condition was matched via voluntary hyperventilation in absence of LBNP in a subgroup of participants (n=8). The mild hypocapnia during LBNP did not exert a confounding influence on the NVC response. These findings indicate that the NVC is not influenced by LBNP or mild hypocapnia in humans. 2021-03-10T18:16:47Z 2021-03-10T18:16:47Z 2020 Artigo SAMORA, Milena et al. Neurovascular coupling is not influenced by lower body negative pressure in humans. American journal of physiology-heart and circulatory physiology, v. 319, n. 1, H22-H31, 2020. DOI: https://doi.org/10.1152/ajpheart.00076.2020. https://repositorio.unb.br/handle/10482/40206 https://doi.org/10.1152/ajpheart.00076.2020 https://orcid.org/0000-0001-6348-1786 https://orcid.org/0000-0002-5747-0295 https://orcid.org/0000-0001-7851-9222 Inglês https://journals.physiology.org/doi/abs/10.1152/ajpheart.00076.2020 Acesso Restrito American Physiological Society
institution	REPOSITORIO UNB
collection	REPOSITORIO UNB
language	Inglês
topic	Circulação cerebral Acoplamento neurovascular Sistema nervoso simpático
spellingShingle	Circulação cerebral Acoplamento neurovascular Sistema nervoso simpático Samora, Milena Vianna, Lauro Casqueiro Carmo, Jake C. Macedo, Victor Dawes, Matthew Phillips, Aaron A. Paton, Julian F. R. Fisher, James P. Neurovascular coupling is not influenced by lower body negative pressure in humans
description	Cerebral blood flow is tightly coupled with local neuronal activation and metabolism, i.e., neurovascular coupling (NVC). Studies suggest a role of sympathetic nervous system in the regulation of cerebral blood flow. However, this is controversial, and the sympathetic regulation of NVC in humans remains unclear. Since impaired NVC has been identified in several chronic diseases associated with a heightened sympathetic activity, we aimed to determine whether reflex-mediated sympathetic activation via lower body negative pressure (LBNP) attenuates NVC in humans. NVC was assessed using a visual stimulation protocol (5 cycles of 30 s eyes closed and 30 s of reading) in 11 healthy participants (aged 24 ± 3 yr). NVC assessments were made under control conditions and during LBNP at -20 and -40 mmHg. Posterior (PCA) and middle (MCA) cerebral artery mean blood velocity (Vmean) and vertebral artery blood flow (VAflow) were simultaneously determined with cardiorespiratory variables. Under control conditions, the visual stimulation evoked a robust increase in PCAVmean (∆18.0 ± 4.5%), a moderate rise in VAflow (∆9.6 ± 4.3%), and a modest increase in MCAVmean (∆3.0 ± 1.9%). The magnitude of NVC response was not affected by mild-to-moderate LBNP (all P > 0.05 for repeated-measures ANOVA). Given the small change that occurred in partial pressure of end-tidal CO2 during LBNP, this hypocapnia condition was matched via voluntary hyperventilation in absence of LBNP in a subgroup of participants (n=8). The mild hypocapnia during LBNP did not exert a confounding influence on the NVC response. These findings indicate that the NVC is not influenced by LBNP or mild hypocapnia in humans.
format	Artigo
author	Samora, Milena Vianna, Lauro Casqueiro Carmo, Jake C. Macedo, Victor Dawes, Matthew Phillips, Aaron A. Paton, Julian F. R. Fisher, James P.
author_sort	Samora, Milena
title	Neurovascular coupling is not influenced by lower body negative pressure in humans
title_short	Neurovascular coupling is not influenced by lower body negative pressure in humans
title_full	Neurovascular coupling is not influenced by lower body negative pressure in humans
title_fullStr	Neurovascular coupling is not influenced by lower body negative pressure in humans
title_full_unstemmed	Neurovascular coupling is not influenced by lower body negative pressure in humans
title_sort	neurovascular coupling is not influenced by lower body negative pressure in humans
publisher	American Physiological Society
publishDate	2021
url	https://repositorio.unb.br/handle/10482/40206 https://doi.org/10.1152/ajpheart.00076.2020 https://orcid.org/0000-0001-6348-1786 https://orcid.org/0000-0002-5747-0295 https://orcid.org/0000-0001-7851-9222
_version_	1695119534123384832
score	13.657419

Neurovascular coupling is not influenced by lower body negative pressure in humans

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