Fraction of glucose catabolized via the Embden-Meyerhof pathway: alloxan-diabetic and fasted rats.

From the radiochemical yields of COZ and of fatty acids obtained when liver slices of normal rats are incubated with various specifically labeled precursors, it has been estimated (1) that about 50 per cent of the glucose molecules catabolized enter the Embden-Meyerhof sequence and the remainder follow an alternative pathway which is very similar or identical with the phosphogluconate oxidation pathway (24). The fraction of glucose molecules catabolized via the Embden-Meyerhof pathway (F or F’) has been calculated by two independent equations. In the evaluation of F (Equation 2 (1)) the assumption was made that the alternative pathway was the phosphogluconate oxidation pathway. The evaluation of F’ (Equation 4 (1)) required no such assumption. Striking alterations in over-all carbohydrate metabolism are known to occur in diabetes and in fasting (5, 6). It was therefore considered of interest to carry out experiments which would permit estimation of F and F’ for liver slices from diabetic and from fasted rats. To this end, the radiochemical yields of COZ and fatty acids from glucose-l-Cl”, glucose-& C14, glucose-6-C14, gluconate-l-C14, gluconate-6-C14, lactate-1-C14, and lactate-3-C” have been determined. From these quantities the r81e of the Embden-Meyerhof pathway in the over-all catabolism of glucose has been estimated.