Activities of Pyruvate Carboxylase, Phosphoenolpyruvate Carboxykinase and Pyruvate Kinase of New Zealand Obese+ (NZO) Mice Livers During Different Phases of Diabetes after Starvation, Cortisol and Insulin Treatment

Abstract

We studied the behavior of activities of pyruvate carboxylase, phospoenolpyruvate carboxykinase and pyruvate kinase in the livers of New Zealand, obese (NZO) mice under various conditions. With increasing age, blood glucose and the enzyme activities of phosphoenolpyruvate carboxykinase and pyruvate carboxylase increased, while the pyruvate kinase decreased. We find a similar action of the enzyme activities of phosphoenolpyruvate carboxykinase and pyruvate carboxylase after starvation and corresponding decreasing enzyme activities of pyruvate kinase. Cortisol shows a significant stimulating effect on phosphoenolpyruvate carboxykinase after six hours and so does insulin ten hours after injection. Insulin effects a decrease of phosphoenolpyruvate carboxykinase and an increase of pyruvate kinase on fed mice as well as on starved mice after 20 hours. Pyruvate carboxylase is not influenced by these hormones.