Regulation of glucose uptake by muscle. 7. Effects of fatty acids, ketone bodies and pyruvate, and of alloxan-diabetes, starvation, hypophysectomy and adrenalectomy, on the concentrations of hexose phosphates, nucleotides and inorganic phosphate in perfused rat heart

Abstract

Newsholme & Starvation of the rat, on the other hand, increased the concentration of hexose monophosphates and diminished that of the diphosphate. Regen, Davis & Morgan (1961) have observed in perfused hearts from alloxan-diabetic rats changes in hexose phosphate concentrations similar to those that we have seen in starvation. The conclusion was drawn from these changes in the concentrations of hexose phosphates that anoxia increased, and starvation and diabetes decreased, the rate of phosphorylation of fructose 6-phosphate to the diphosphate catalysed by phosphofructokinase (Newsholme & Randle, 1961, 1962; Newsholme, Randle & Manchester, 1962). The cause of these changes in the rate of the phosphofructokinase reaction was not known. In the studies described below the effects of fatty acids and ketone bodies in vitro on the concentrations of hexose phosphates in the perfused rat heart have been investigated and compared with those seen in diabetes and starvation. They were prompted by the idea that the changes seen in diabetes and starvation might be due to an increased avail- ability of fatty acids and ketone bodies for respira- tion in these conditions. It has now been shown that these substrates can induce changes in hexose phosphate concentrations in hearts from normal fed rats that are similar to those seen in hearts from diabetic or starved rats.