CORRELATION BETWEEN THE LEVELS OF GLUCOSE 1,6-DIPHOSPHATE AND THE ACTIVITIES OF PHOSPHOFRUCTOKINASE, PHOSPHOGLUCOMUTASE AND HEXOKINASE, IN SKELETAL AND HEART MUSCLES FROM RATS OF DIFFERENT AGES

1. 1. The levels of glucose 1,6-diphosphate (Glc-1,6-P2), the positive effector of phosphofructokinase and phosphoglucomutase and inhibitor of hexokinase, were found to increase markedly in skeletal muscle with growth of the rat. This increase in Glc-1,6-P2 was accompanied by a concomitant activation of phosphofructokinase and phosphoglucomutase and a reduction in hexokinase activity. 2. 2. In contrast to skeletal muscle, the rat heart exhibited no age-related changes in Glc-1,6-P2 levels and in the activities of the three enzymes. 3. 3. The striking correlation between the levels of Glc-1,6-P2 and the activities of the three enzymes which are regulated by this effector, strongly suggests that the age-related changes in the enzymes' activities in skeletal muscle are mediated by changes in the tissue levels of Glc-1,6-P2. © 1979.