Muscle mechanoreflex mediates vasoconstriction in inactive limb in rats

We determined whether, stimulation of mechanosensitive receptors in active muscle (muscle mechanoreflex activation) induces vasoconstriction in the contralateral non-active muscles. In mid-collicular decerebrated rats (n = 9), we measured the blood flow of the left iliac artery when the right Achilles tendon was stretched by 300 g for 30 seconds (s) to stimulate mechanoreceptors in the triceps surae muscles. The stretch significantly increased the mean arterial pressure (MAP: +20 ± 3%, peak increase from baseline; mean ± SEM) and decreased the vascular conductance (VC) in the left iliac artery (–9 ± 1%, averaged over the stimulation period). After cutting the left sciatic nerve, the stretch did not significantly change the VC (+5 ± 1%), while it significantly increased MAP (+13 ± 3%, peak). In conclusion, the muscle mechanoreflex plays a role in mediating vasoconstriction in the contralateral limb via sympathetic activation.