Hexose metabolism in pancreatic islets: effect of D-glucose on the mitochondrial redox state.
The mitochondrial NADH/NAD+ ratio for free nucleotides in rat pancreatic islets was judged from the cell content in L-glutamate and L-alanine, 2-ketoglutarate and pyruvate, and NH4+. At a physiological concentration of D-glucose, such a ratio averaged 9.6 +/- 1.1%. A rise in hexose concentrations, above a threshold value in excess of 5.6 mM, caused a rapid, sustained and rapidly reversible decrease in the mitochondrial NADH/NAD+ ratio. It is speculated that in the process of glucose-stimulated insulin release, the latter change participates in the coupling between metabolic and secretory events by favouring both the activity of key mitochondrial dehydrogenases and the translocation of Ca2+ from the mitochondria into the cytosol.
Ramirez
R
R
Laboratory of Experimental Medicine, Erasmus Medical School, Brussels Free University, Belgium.
Sener
A
A
Malaisse
W J
WJ
D000818:Animals; D005947:Glucose / Q000378:metabolism*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010086:Oxidative Phosphorylation Coupling Factors / Q000378:metabolism; D051381:Rats
D010086:Oxidative Phosphorylation Coupling Factors; D009243:NAD; D005947:Glucose