Effects of partial neuromuscular blockade on carotid baroreflex function during exercise in humans
Article first published online: 5 AUG 2004
The Journal of Physiology
Volume 533, Issue 3, pages 861–870, June 2001
How to Cite
Gallagher, K. M., Fadel, P. J., Strømstad, M., Ide, K., Smith, S. A., Querry, R. G., Raven, P. B. and Secher, N. H. (2001), Effects of partial neuromuscular blockade on carotid baroreflex function during exercise in humans. The Journal of Physiology, 533: 861–870. doi: 10.1111/j.1469-7793.2001.t01-1-00861.x
- Issue published online: 5 AUG 2004
- Article first published online: 5 AUG 2004
- (Received 22 June 2000; accepted after revision 1 February 2001)
- 1This investigation was designed to determine the contribution of central command to the resetting of the carotid baroreflex during static and dynamic exercise in humans.
- 2Thirteen 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.
- 3Partial 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).
- 4These findings suggest that central command actively resets the carotid baroreflex during dynamic and static exercise.