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Relevance of lactate dehydrogenase activity to the control of oxidative glycolysis in pancreatic islet B-cells.

par Jijakli, Hassan ;Rasschaert, Joanne ;Bakkali Nadi, Abdellatif ;Leclercq Meyer, Viviane ;Sener, Abdullah ;Malaisse, Willy
Référence Archives of biochemistry and biophysics, 327, 2, page (260-264)
Publication Publié, 1996-03

Article révisé par les pairs

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Résumé :

The activities of hexokinase isoenzymes, lactate dehydrogenase, cytosolic NAD-linked glycerophosphate dehydrogenase, mitochondrial FAD-linked glycerophosphate dehydrogenase, and glutamate dehydrogenase were measured in homogenates of rat purified pancreatic B and non-B islet cells. In B cell homogenates, the maximal activity of hexokinase and glucokinase was one to two orders of magnitude lower than that of lactate dehydrogenase. The activity of the mitochondrial FAD-linked glycerophosphate dehydrogenase was also much lower than that of the cytosolic NAD-linked glycerophosphate dehydrogenase . A comparable hierarchy in the activity of these enzymes was observed in non-B islet cells. These findings reinforce the view that the preferential stimulation of oxidative glycolysis observed in insulin-producing cells, when exposed to high concentrations of D-glucose, is attributable to a Ca2+-induced activation of the mitochondrial FAD-linked glycerophosphate dehydrogenase, rather than to saturation of the catalytic activity of lactate dehydrogenase.