Stability of hexokinases A, B and C and N-acetylglucosamine kinase in liver cells isolated from rats submitted to diabetes and several dietary conditions

Abstract

The effect of dietary and hormonal variations on the specific activities of hexokinase isoenzymes, N-acetylglucosamine kinase and pyruvate kinase isoenzymes in parenchymal and non-parenchymal liver cells was studied. Hexokinase D was markedly decreased in hepatocytes from animals fasted or fed on the carbohydrate-free diet as well as from diabetic rats, attaining a constant low level of about 17% of normal values. Pyruvate kinase L was also diminished in hepatocytes under the same experimental conditions. In contrast, the three high-affinity hexokinase isoenzymes A, B and C remained without variation in total amount or in their relative proportions in hepatocytes and non-parenchymal liver cells isolated from animals under the various conditions studied. N-Acetylglucosamine kinase activities also did not change either in parenchymal or in non-parenchymal liver cells under all conditions. The results are discussed in relation to the significance of N-acetylglucosamine kinase and the various hexokinase isoenzymes for the phosphorylation of glucose after dietary and hormonal manipulations.