Kinetic behaviour of liver glucokinase in diabetes. III. Possible role of insulinopenia.

: In both starved and diazoxide-treated rats, the rate of D-(U-14C)glucose phosphorylation (10 mM) by liver cytosol, as measured in the presence of D-glucose 6-phosphate, was lower than in fed control rats. Moreover, in these two models of insulinopenia, the sensitivity of glucokinase to a lowering of temperature from 30 degrees C to 10 degrees C and its apparent affinity for D-glucose were both decreased. Such kinetic anomalies could not be attributed to the restricted contribution of N-acetyl-D-glucosamine kinase to the phosphorylation of D-glucose. It is proposed, therefore, that insulin deficiency may lead to a perturbation in either the intrinsic kinetic behaviour of glucokinase or the participation of its regulatory protein, independently of any change in glycemia.