Hexose metabolism in pancreatic islets. Insignificance of D-glucose futile cycling in rat islets
Liemans, V.; Sener, A.; Malaisse, W.J.
Biochemistry International 24(2): 391-396
1991
ISSN/ISBN: 0158-5231 PMID: 1656983 Document Number: 377805
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.