Effects of exercise pressor reflex activation on carotid baroreflex function during exercise in humans
Article first published online: 5 AUG 2004
The Journal of Physiology
Volume 533, Issue 3, pages 871–880, 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 exercise pressor reflex activation on carotid baroreflex function during exercise in humans. The Journal of Physiology, 533: 871–880. doi: 10.1111/j.1469-7793.2001.t01-2-00871.x
- Issue published online: 5 AUG 2004
- Article first published online: 5 AUG 2004
- (Received 29 June 2000; accepted after revision 1 February 2001)
- 1This investigation was designed to determine the contribution of the exercise pressor reflex to the resetting of the carotid baroreflex during exercise.
- 2Ten 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.
- 3During 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.
- 4These 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.