Stimulation of both aerobic glycolysis and Na+-K+-ATPase activity in skeletal muscle by epinephrine or amylin

Epinephrine and amylin stimulate glycogenolysis, glycolysis, and Na+-K+-ATP ase activity in skeletal muscle. However, it is not known whether these hor mones stimulate glycolytic ATP production that is specifically coupled to A TP consumption by the Na+-K+ pump. These studies correlated glycolysis with Na+-K+-ATPase activity in resting rat extensor digitorum longus and soleus muscles incubated at 30 degrees C in well-oxygenated medium. Lactate produ ction rose three- to fourfold, and the intracellular Na+-to-K+ ratio (Na+/K +) fell with increasing concentrations of epinephrine or amylin. In muscles exposed to epinephrine at high concentrations (5 x 10(-7) and 5 x 10(-6) M ), ouabain significantly inhibited glycolysis by similar to 70% in either m uscle and inhibited glycogenolysis by similar to 40 and similar to 75% in e xtensor digitorum longus and soleus, respectively. In the absence of ouabai n, but not in its presence, statistically significant inverse correlations mere observed between lactate production and intracellular Na+/K+ for each hormone. Epinephrine had no significant effect on oxygen consumption or ATP content in either muscle. These results suggest for the first time that st imulation of glycolysis and glycogenolysis in resting skeletal muscle by ep inephrine or amylin is closely Linked to stimulation of active Na+-K+ trans port.