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.
Zähner
D
D
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Ramirez
R
R
Malaisse
W J
WJ
D000117:Acetylglucosamine / Q000378:metabolism; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology*; D003981:Diazoxide / Q000494:pharmacology; D005260:Female; D005941:Glucokinase / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism; D006442:Glycated Hemoglobin / Q000032:analysis; D006023:Glycoproteins / Q000032:analysis / Q000378:metabolism; D006031:Glycosylation; D007328:Insulin / Q000097:blood / Q000502:physiology*; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013217:Starvation; D013379:Substrate Specificity
D000117:Acetylglucosamine; D001786:Blood Glucose; D003981:Diazoxide; D005941:Glucokinase; D005947:Glucose; D006442:Glycated Hemoglobin; D006023:Glycoproteins; D007328:Insulin