Effect of Exercise and Dietary Carbohydrate on Glucose Oxidation in Rats

Abstract

Summary

The effect of high-fat vs high-carbohydrate diets on the relative role of the pentose cycle (PC) in glucose catabolism was studied in exercised and sedentary rats fed different carbohydrate sources. Expired ¹⁴CO₂ was measured after injection of ¹⁴C-glucose labeled at C-1 or C-6 or at all carbons, and data were fitted to an experimental model. Ad libitum fed Sprague-Dawley rats appeared to show a diurnal rhythm in the degree of utilization of the PC in glucose catabolism. Exercise of calorically restricted animals reduced the relative role of the PC; but altering the fat:carbohydrate ratio of the diet of ad libitum fed animals had no apparent effect. Under a variety of conditions, at least 25% of the glucose which entered relatively labile pools was selectively decar-boxylated at the C-1 position.