PERFUSED SKELETAL-MUSCLE CONTRACTION AND METABOLISM IMPROVED BY ANGIOTENSIN II-MEDIATED VASOCONSTRICTION

In the present study, the effects of angiotensin II (ANG II) on tensio n development and associated metabolism during twitch and tetanic stim ulation via the sciatic nerve of the gastrocnemius-plantaris-soleus mu scle group of the perfused rat hindlimb were investigated. Rat hindlim bs were perfused at constant flow with an erythrocyte-containing mediu m equilibrated with 95% air-5% CO2 at 37 degrees C, and determinations of oxygen and glucose uptake, lactate and glycerol release, and 2-deo xy-D-[1-H-3]glucose uptake (R(g)') into individual muscles were carrie d out. ANG II (1 nM) infusion alone caused vasoconstriction with incre ased oxygen (55%) and glucose (98%) uptake and lactate (37%) and glyce rol (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 uptak e and R(g)' by plantaris and gastrocnemius red and white muscles. Thes e effects of ANG II may have been due to increased nutritive flow to c ontracting muscles or to redirection of flow from noncontracting and t ype I fiber muscles to the type II fiber contracting muscles in the hi ndlimb. The results indicate that the regulation of flow by the vascul ature is an important regulator of muscle contraction and metabolism.