Contributions of dietary carbohydrate and ethanol to alterations in liver glycogen levels and glycolytic activity

Hepatic glycogen levels are decreased in rats as a consequence of chronic ethanol consumption. In earlier studies ethanol (36% of total calories consumed) replaced carbohydrate in the ethanol-containing diet, thus leading to the possibility that the decreases in liver glycogen were a result of limited dietary carbohydrate. In the present study, rats were administered ethanol in low-carbohydrate (LC) or high-carbohydrate (HC) diets to determine if lowered dietary carbohydrate contributes to the decrease in glycogen levels associated with ethanol consumption. The glycogen content of isolated hepatocytes was not different between rats fed LC or HC in control or ethanol-containing diets. Lactate and pyruvate were measured to determine the effects of dietary carbohydrate and ethanol on glycolytic activity, and were not significantly altered by changes in the levels of dietary carbohydrate. However, ethanol-containing diets resulted in decreased concentrations of hepatic glycogen, lactate, and pyruvate as compared with controls in both LC and HC diets. These observations demonstrate that decreases in glycogen content and lactate + pyruvate concentrations are due to chronic ethanol consumption rather than a carbohydrate deficiency, when carbohydrate is maintained above 10% of total calories. (C) 1999 Elsevier Science Inc. All rights reserved.