Metabolic effects of acarbose administration in normal and diabetic rats

Abstract

The effect of acarbose on cardiac and hepatic metabolism was investigated in normal and diabetic rats. Groups of rats were fed one of the three following diets for 7 days: (1) ground Purina chow, (2) ground Purina chow fortified with raw corn starch and sucrose, and (3) the above high carbohydrate diet, with added acarbose (40 mg/100 g food). At the end of the dietary period the rats were decapitated, and a sample of liver tissue was removed and frozen in liquid nitrogen. The heart was extirpated for subsequent perfusion by the Langendorff technique. Increases in liver and heart glycogen produced by the high carbohydrate diet in the normal rats were prevented completely when acarbose was incorporated into the food. In diabetic animals, liver glycogen was uniformly lower than normal, irrespective of the diet or the presence of acarbose. With animals fed the control diet, cardiac glycogen was higher in diabetic than in normal rats. The high carbohydrate diet caused a lowering of heart glycogen in diabetic rats and this reduction in glycogen content was reversed by including acarbose in the diet. Effects of isoproterenol on myocardial phosphorylase a activity were determined in hearts from normal and diabetic rats given one of the three diets. The high carbohydrate diet decreased the enzymatic response to the catecholamine in hearts from both normal and diabetic animals, and this phenomenon was prevented by the presence of acarbose in the diet. In diabetic rats fed any of the three diets, the activation of cardiac phosphorylase by isoproterenol was greatly accentuated. Measurements of heart uridine kinase showed that the activity of this enzyme was lower than normal in hearts from diabetic rats given either the control or the high carbohydrate diet. The presence of acarbose in the latter diet resulted in a significant decrease in cardiac uridine kinase activity in hearts from normal rats. The results of this study demonstrate the effectiveness of acarbose in modulating tissue metabolism in normal and diabetic animals.