Pathways of Carbohydrate Formation in Man. I. Isotope Distribution in Glucose from Nondiabetic Subjects Given 1-C14-Acetate12

Abstract

To 4 post-absorptive patients with carcinoma, but presumably normal carbohydrate metabolism, were given single intravenous injections of trace amounts of l-C14-acetate followed by collection, isolation, and degradation of blood glucose by various bacteriological and chemical methods. Virtually all of the glucose C14 was found in the 3 and 4 carbon positions (about equally distributed) with 1 to 2% of the total glucose C14 in each of the other (1, 2, 5, and 6) positions. About 1.5% of the administered C14 was present in free body glucose at 2 hours after injection. Findings are consistent with operation of the tricarboxylic acid cycle and glycolytic pathways as the principal routes for conversion of fatty acid to carbohydrate.