Hyperpyruvaturia in experimental diabetes

Abstract

The 24 hourly excretion of pyruvate and glucose has been measured in alloxan-diabetic rats. The animals were allowed a 6-day control period before being injected with alloxan (I.V. 50 mg/ kg body weight). The diabetes was treated by daily injections of insulin for a period of 6 days from the 7th to the 12th day following the alloxan injection. The pyruvate excretion increased more than 5-fold following the induction of diabetes, the values being 189 [plus or minus] 130 (S.D.) [mu]g/24 hr in the control period rising to an average of 1002 [plus or minus] 664 S.D.) [mu]g/24 hr over the first 6 days of diabetes. The adminis-tration of insulin over the second 6-day period of diabetes caused the pyruvate excretion to decrease[long dash]though not significantly. Upon the withdrawal of the insulin treatment the pyruvate excretion increased significantly from 785 [plus or minus] 315 (S.D.) [mu]g/24 hr to 2105 [plus or minus] 679 (S.D.) [mu]g/24 hr, measured over a 5-day period. The final period of pyruvate excretion over the first diabetic period. The glucose excretion during the initial diabetic period was 6.75 [plus or minus] 2.64 (S.D.) g/24 hr. The administration of insulin caused a 42% decrease in glucose excretion compared to a decrease of 22% for the pyruvate. The withdrawal of insulin caused the glucose excretion to increase by 149% while the pyruvate excretion increased by 157%. Diabetes was also induced temporarily by injections of anti-insulin serum and diazoxide. In each case significant glycosuria and hyperpyruvaturia were produced. The possible causes of the hyperpyruvaturia in diabetes are discussed.