Perfused skeletal muscle contraction and metabolism improved by angiotensin II-mediated vasoconstriction

In the present study, the effects of angiotensin II (ANG II) on tension development and associated metabolism during twitch and tetanic stimulation via the sciatic nerve of the gastrocnemius-plantaris-soleus muscle group of the perfused rat hindlimb were investigated. Rat hindlimbs were perfused at constant flow with an erythrocyte-containing medium equilibrated with 95% air-5% CO2 at 37 degrees C, and determinations of oxygen and glucose uptake, lactate and glycerol release, and 2-deoxy-D-[1-3H]glucose uptake (Rg') into individual muscles were carried out. ANG II (1 nM) infusion alone caused vasoconstriction with increased oxygen (55%) and glucose (98%) uptake and lactate (37%) and glycerol (64%) release. ANG II infusion during muscle contraction gave less vasoconstriction but increased the tension development during tetanic stimulation by 80% and increased the contraction-induced oxygen uptake and Rg' by plantaris and gastrocnemius red and white muscles. These effects of ANG II may have been due to increased nutritive flow to contracting muscles or to redirection of flow from noncontracting and type I fiber muscles to the type II fiber contracting muscles in the hindlimb. The results indicate that the regulation of flow by the vasculature is an important regulator of muscle contraction and metabolism.