Effects of Dietary Composition on Glucose Metabolism in Rat Adipose Cells

The effect of altered dietary carbohydrate and fat content on equilibrium insulin binding to, and glucose transport activity and metabolism in, isolated rat epididymal adipose cells has been studied. Alterations in basal and insulin-stimulated total glucose utilization induced by changes in the ratio of dietary carbohydrate to fat are accounted for by specific effects of dietary composition at two levels of cellular function: 1) glucose transport across the cell's plasma membrane, specifically, the number of functional glucose transport systems, and 2) the cell's maximal capacity for glucose metabolism. These effects occur without alterations in insulin binding or the cell's sensitivity to insulin. Furthermore, diet-induced changes in the pattern of 14CO2, and 14C-triglyceride glycerol and fatty acid production appear to be accounted for primarily by the influence of dietary composition on the total amount of glucose entering the cell. Thus, under the conditions of this study, changes in dietary composition alter the adipose cell's capacities for glucose transport and metabolism without altering the mechanisms of insulin action or regulating the metabolic flow of glucose carbons.