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Effects of exercise pressor reflex activation on carotid baroreflex function during exercise in humans1. This investigation was designed to determine the contribution of the exercise pressor reflex to the resetting of the carotid baroreflex during exercise. 2. Ten subjects performed 3.5 min of static one-legged exercise (20 % maximal voluntary contraction) and 7 min dynamic cycling (20 % maximal oxygen uptake) under two conditions: control (no intervention) and with the application of medical anti-shock (MAS) trousers inflated to 100 mmHg (to activate the exercise pressor reflex). Carotid baroreflex function was determined at rest and during exercise using a rapid neck pressure/neck suction technique. 3. During exercise, the application of MAS trousers (MAS condition) increased mean arterial pressure (MAP), plasma noradrenaline concentration (dynamic exercise only) and perceived exertion (dynamic exercise only) when compared to control (P < 0.05). No effect of the MAS condition was evident at rest. The MAS condition had no effect on heart rate (HR), plasma lactate and adrenaline concentrations or oxygen uptake at rest and during exercise. The carotid baroreflex stimulus-response curve was reset upward on the response arm and rightward to a higher operating pressure by control exercise without alterations in gain. Activation of the exercise pressor reflex by MAS trousers further reset carotid baroreflex control of MAP, as indicated by the upward and rightward relocation of the curve. However, carotid baroreflex control of HR was only shifted rightward to higher operating pressures by MAS trousers. The sensitivity of the carotid baroreflex was unaltered by exercise pressor reflex activation. 4. These findings suggest that during dynamic and static exercise the exercise pressor reflex is capable of actively resetting carotid baroreflex control of mean arterial pressure; however, it would appear only to modulate carotid baroreflex control of heart rate.
Document ID
20040112401
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Gallagher, K. M.
(University of North Texas Health Science Center Fort Worth, TX 76107, United States)
Fadel, P. J.
Stromstad, M.
Ide, K.
Smith, S. A.
Querry, R. G.
Raven, P. B.
Secher, N. H.
Date Acquired
August 21, 2013
Publication Date
June 15, 2001
Publication Information
Publication: The Journal of physiology
Volume: 533
Issue: Pt 3
ISSN: 0022-3751
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: 45547
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Cardiopulmonary

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