Studies were performed to investigate the hormonal regulation and the effects of exercise, anoxia, and fasting on the regulation of glycolysis, glucose oxidation, and energy metabolism in human skeletal muscle. In particular, investigations were focused on glucose 1,6-bisphosphate (GP2) as a possible important regulator of Glycolysis, since previous studies had shown it to increase in parallel with glycolysis after isometric contraction of the muscle to fatigue. Glucose metabolites, in muscle during prolonged fasting are currently being analyzed. However, GP2 increases in human skeletal muscle following either isometric contraction, anoxia, circulatory occlusion, and in response to insulin and epinephrine. There is no increase in GP2 when glucose is infused in the absence of insulin. GP2 activation may be a result of activation of GP2 synthase by its substrates glucose 1-phosphate (G1P) and glucose 6-phosphate (G6P). Thus, it appears that GP2 may have a significant role to play in stimulating glycolysis under a variety of metabolic conditions in human skeletal muscle. The ultimate mechanism involves the activation of phosphofructokinase by GP2.
