ACTIVATION OF GLYCOGEN-PHOSPHORYLASE AND GLYCOGENOLYSIS IN RAT SKELETAL-MUSCLE BY AICAR - AN ACTIVATOR OF AMP-ACTIVATED PROTEIN-KINASE

We determined whether the cell permeable molecule AICAR, whose metabol ite activates AMP-activated protein kinase (AMPK) in cells, affected g lycogen metabolism in rat soleus muscle preparations in vitro. The bas al and insulin-stimulated rates of radiochemical lactate formation, ne t lactate release and glycogen synthesis were determined. AICAR stimul ated net lactate release (but not radiochemical lactate formation) onl y at a basal concentration of insulin. An increased rate of glycogenol ysis was the likely cause of increased net lactate release as glycogen phosphorylase activity was significantly increased by AICAR, AICAR-st imulated net lactate release and phosphorylase activity were potently inhibited by insulin.