Hexose metabolism in pancreatic islets. Regulation of aerobic glycolysis and pyruvate decarboxylation.
1. D-Glucose (0.5-16.7 mM) preferentially stimulates aerobic glycolysis and D-[3,4-14C]glucose oxidation, relative to D-[5-3H]glucose utilization in rat pancreatic islets, the concentration dependency of such a preferential effect displaying a sigmoidal pattern. 2. Inorganic and organic calcium antagonists, as well as Ca2+ deprivation, only cause a minor decrease in the ratio between D-[3,4-14C]glucose oxidation and D-[5-3H]glucose utilization in islets exposed to a high concentration of the hexose (16.7 mM). 3. Non-glucidic nutrient secretagogues such as 2-aminobicyclo[2,2,1]heptane-2-carboxylate (BCH), 2-ketoisocaproate and 3-phenylpyruvate fail to stimulate aerobic glycolysis and D-[3,4-14C]glucose oxidation in islets exposed to 6.0 mM D-glucose. Nevertheless, BCH augments [1-14C]pyruvate and [2-14C]pyruvate oxidation. 4. The glucose-induced increment in the paired ratio between D-[3,4-14C]glucose oxidation and D-[5-3H]glucose utilization is impaired in the presence of either cycloheximide or ouabain. 5. These findings suggest that the preferential effect of D-glucose upon aerobic glycolysis and pyruvate decarboxylation is not attributable solely to a Ca(2+)-induced activation of FAD-linked glycerophosphate dehydrogenase and/or pyruvate dehydrogenase, but may also involve an ATP-modulated regulatory process.
Malaisse
W J
WJ
Labortory of Experimental Medicine, Brussels Free University, Belgium.
Rasschaert
J
J
Conget
I
I
Sener
A
A
D000332:Aerobiosis; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D003513:Cycloheximide / Q000494:pharmacology; D003653:Decarboxylation; D005947:Glucose / Q000494:pharmacology; D006019:Glycolysis; D006601:Hexoses / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D010084:Oxidation-Reduction; D011773:Pyruvates / Q000378:metabolism*; D019289:Pyruvic Acid; D051381:Rats
D006601:Hexoses; D011773:Pyruvates; D010042:Ouabain; D019289:Pyruvic Acid; D003513:Cycloheximide; D005947:Glucose; D002118:Calcium