Hepatic glycolytic enzyme activities in the alloxan-diabetic rat: response to glucose and fructose feeding.

In an earlier report (1) we compared the responses of hepatic glycolytic enzyme activities of normal rats fed either glucose or fructose for 3 days. The enzymes studied were phosphoglucomutase, glucose 6-phosphatase, phosphoglucose isomerase, and the dehydrogenases of glucose B-phosphate and gluconate g-phosphate. When the diets containing free hexoses were substituted for the stock diet, the activities of isomerase and both dehydrogenases were augmented, but the response to fructose feeding exceeded by far that observed with glucose. Only the fructose diet augmented the phosphatase activity, whereas neither diet affected the mutase activity. The present report concerns the responses to hexose feeding of these hepatic enzymes in the diabetic rat. It is shown that the magnitude of response to either hexose by the diabetic rat does not approach that by the normal rat. Our findings indicate that the liver of the diabetic rat is characterized by a reduced response to the substitution of hexose-containing diets.