Hexose metabolism in pancreatic islets. Insignificance of D-glucose futile cycling in rat islets.
When rat pancreatic islets were incubated in the presence of unlabelled D-glucose (16.7 mM) and 3HOH, the production of 3H-labelled material susceptible to be phosphorylated by yeast hexokinase and then detritiated by yeast phosphoglucoisomerase did not exceed 2.66 +/- 0.21 pmol/islet per 180 min, i.e. about 1% of the rate of exogenous D-[5-3H]glucose utilization. Such a material accounted for 43 +/- 4% of the total radioactivity, associated with tritiated hexose(s). It is proposed, therefore, that the futile cycling of D-glucose in the reactions catalyzed in the islet cells by the hexokinase isoenzymes and glucose-6-phosphatase represents a negligible fraction of the total rate of D-glucose phosphorylation.
Liemans
V
V
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Sener
A
A
Malaisse
W J
WJ
D000818:Animals; D002478:Cells, Cultured; D005260:Female; D005941:Glucokinase / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D005952:Glucose-6-Phosphatase / Q000378:metabolism*; D005956:Glucose-6-Phosphate Isomerase / Q000378:metabolism; D006601:Hexoses / Q000737:chemistry / Q000378:metabolism*; D007515:Islets of Langerhans / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D051381:Rats
D006601:Hexoses; D005941:Glucokinase; D005952:Glucose-6-Phosphatase; D005956:Glucose-6-Phosphate Isomerase; D005947:Glucose