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Effects of partial neuromuscular blockade on carotid baroreflex function during exercise in humans
Author(s) -
Gallagher K. M.,
Fadel P. J.,
Strømstad M.,
Ide K.,
Smith S. A.,
Querry R. G.,
Raven P. B.,
Secher N. H.
Publication year - 2001
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2001.t01-1-00861.x
Subject(s) - baroreflex , neuromuscular blockade , heart rate , medicine , anesthesia , blockade , reflex , cardiology , blood pressure , receptor
1 This investigation was designed to determine the contribution of central command to the resetting of the carotid baroreflex during static and dynamic exercise in humans. 2 Thirteen 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 partial neuromuscular blockade (to increase central command influence) using Norcuron (curare). Carotid baroreflex function was determined at rest and during steady‐state exercise using a rapid neck pressure/neck suction technique. Whole‐body Norcuron was repeatedly administered to effectively reduce hand‐grip strength by approximately 50 % of control. 3 Partial neuromuscular blockade increased heart rate, mean arterial pressure, perceived exertion, lactate concentration and plasma noradrenaline concentration during both static and dynamic exercise when compared to control ( P < 0.05 ). No effect was seen at rest. Carotid baroreflex resetting was augmented from control static and dynamic exercise by partial neuromuscular blockade without alterations in gain ( P < 0.05 ). In addition, the operating point of the reflex was relocated away from the centring point (i.e. closer to threshold) during exercise by partial neuromuscular blockade ( P < 0.05 ). 4 These findings suggest that central command actively resets the carotid baroreflex during dynamic and static exercise.