Hexose metabolism in pancreatic islets. Ca(2+)-dependent activation of the glycerol phosphate shuttle by nutrient secretagogues.
A method is proposed for the measurement of the flux through the glycerol phosphate shuttle in pancreatic islets. Such a flux is taken as the ratio between the production of 3HOH and the specific radioactivity of L-[2-3H]glycerophosphate in islets exposed to [2-3H]glycerol. D-Glucose and non-glucidic nutrient secretagogues, such as 2-ketoisocaproate and 2-aminobicyclo[2,2,1]heptane-2-carboxylate, stimulate, in a Ca(2+)-dependent manner, circulation in the glycerol phosphate shuttle. The shuttle flux is commensurate with the fraction of pyruvate generation which is not coupled with L-lactate production. These findings support the view that a rise in D-glucose concentration leads to activation of the FAD-linked mitochondrial glycerophosphate dehydrogenase through an increase in cytosolic Ca2+ concentration.
Sener
A
A
Laboratory of Experimental Medicine, Brussels Free University, Belgium.
Malaisse
W J
WJ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent; D005260:Female; D005990:Glycerol / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism*; D006601:Hexoses / Q000378:metabolism*; D007515:Islets of Langerhans / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats
D002413:Cations, Divalent; D005994:Glycerophosphates; D006601:Hexoses; D005990:Glycerol; D002118:Calcium