Carotid baroreflex control of leg vascular conductance at rest and during exercise.
We sought to test the hypothesis that the carotid baroreflex (CBR) alters mean leg blood flow (LBF) and leg vascular conductance (LVC) at rest and during exercise. In seven men and one woman, 25 +/- 2 (SE) yr of age, CBR control of LBF and LVC was determined at rest and during steady-state one-legged knee extension exercise at approximately 65% peak O(2) uptake. The application of 5-s pulses of +40 Torr neck pressure and -60 Torr neck suction significantly altered mean arterial pressure (MAP) and LVC both at rest and during exercise. CBR-mediated changes in MAP were similar between rest and exercise (P > 0.05). However, CBR-mediated decreases in LVC (%change) to neck pressure were attenuated in the exercising leg (16.4 +/- 1.6%) compared with rest (33 +/- 2.1%) and the nonexercising leg (23.7 +/- 1.9%) (P < 0.01). These data suggest CBR control of blood pressure is partially mediated by changes in leg vascular tone both at rest and during exercise. Furthermore, despite alterations in CBR-induced changes in LVC during exercise, CBR control of blood pressure was well maintained.
Keller
David M
DM
Department of Integrative Physiology, University of North Texas Health Science Center, Fort Worth 76107, USA. dkeller@hsc.unt.edu
Wasmund
Wendy L
WL
Wray
D Walter
DW
Ogoh
Shigehiko
S
Fadel
Paul J
PJ
Smith
Michael L
ML
Raven
Peter B
PB
D000328:Adult; D017704:Baroreflex / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002339:Carotid Arteries / Q000294:innervation*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007717:Knee / Q000502:physiology; D007866:Leg / Q000098:blood supply*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D010101:Oxygen Consumption; D012039:Regional Blood Flow / Q000502:physiology; D012146:Rest