MUSCLE CHEMOREFLEX ALTERS VASCULAR CONDUCTANCE IN NONISCHEMIC EXERCISING SKELETAL-MUSCLE

Previous studies have shown that the muscle chemoreflex causes an augm ented blood pressure response to exercise and partially restores blood flow to ischemic muscle. The purpose of this study was to investigate the effects of the muscle chemoreflex on blood flow to nonischemic ex ercising skeletal muscle. During each experiment, dogs ran at 10 kph f or 8-16 min and the muscle chemoreflex was evoked by reducing hindlimb blood flow at 4-min intervals (0-80%). Arterial blood pressure, hindl imb blood flow, forelimb blood flow, and forelimb vascular conductance were averaged over the last minute at each level of occlusion. Stimul ation of the muscle chemoreflex caused increases in arterial blood pre ssure and forelimb blood flow and decreases in forelimb vascular condu ctance. The decrease in forelimb vascular conductance demonstrates tha t the muscle chemoreflex causes vasoconstriction in the nonischemic ex ercising forelimb. Despite the decrease in vascular conductance, the i ncreased driving pressure caused by the presser response was large eno ugh to produce an increased forelimb blood flow.