Abstract
We determined whether exercise pressor reflex (sensory afferent input from muscle to the medulla) decreases vascular conductance in an inactive contralateral limb as to increase blood flow to the active muscle. Sprague Dawley rats (n=9) were instrumented with electro-magnetic flow probe (MFV2100, 1mm probe; Nihon-Koden) on left iliac artery and a catheter in carotid artery. Rats were decerebrated at midcollicular level. Right triceps surae muscles were exposed and the Achilles tendon was ligated. The tendon was stretched at 300 g for 30 s to stimulate the muscle. The vascular conductance (VC) of left inactive leg was calculated from mean arterial pressure (MAP) and iliac blood flow. The stretch significantly increased the MAP (+20±3％, peak increase from baseline; mean±SEM), while it significantly decreased the VC in the left iliac artery (–9±1％, average over stimulation period). After cutting the left sciatic nerve, the stretch significantly increased MAP (+13±3％, peak), but did not significantly change the VC in the inactive left iliac artery (+5±1％, average). This result suggests that exercise pressor reflex induces sympathetic vasoconstriction in the inactive contralateral muscle. [Jpn J Physiol 54 Suppl:S95 (2004)]
