Role of Inorganic Phosphate in Active Hyperemia in Skeletal Muscle

Abstract

Summary

The purpose of this study was to determine the extent of involvement of the inorganic phosphate ion (Pi) in exercise hyperemia. Lymph and venous plasma from resting and contracting muscles of the canine and feline hindlimbs were analyzed for Pi. The vasoactivity of exogenous inorganic phosphate was assessed by close intra-arterial infusion of the sodium monobasic phosphate while blood flow and lymph and venous plasma Pi concentrations were determined. The results showed that there was no increase in venous plasma Pi with muscle contraction, only a small increase in lymph Pi, and that the phosphate ion is very vasoinactive. We therefore conclude that the inorganic phosphate ion may play only a minor role, if any, in active hyperemia in skeletal muscle.