THE METABOLISM OF D-RIBOSE IN MAN

Open Access
Publisher Website
Google Scholar
Abstract
The metabolism of D-ribose was studied in man by the infusion of both C-labeled and unlabeled sugar. The sugar disappeared rapidly from blood. However, when doses above 3 g were given there appeared to be saturation of the system. The pentose was found to be rapidly and extensively metabolized, a principal fate being conversion to body glucose via the pentose phosphate pathway. About 50% of the activity in C14-ribose given in trace quantity appeared as expired C14(O)2 within 6 hours. Although converted to glucose, ribose infusion caused a lowering of blood glucose but caused no change in serum inorganic phosphate or blood pyruvate. It was shown that ribose-5-phosphate may inhibit the enzyme phosphoglucomutase, thus providing a possible explanation for the cause of the ribose induced hypoglycemia, that is, the prevention of hepatic glycogen breakdown. Ribose was found to be insulin responsive for insulin caused a lowering of blood ribose levels. Urinary excretion of infused ribose varied with the rate of infusion. About 20% of a 20 g infusion given in 15 minutes was renally excreted.