NADP-linked dismutation and concentrations of citrate, cytosolic free Ca2+ and phosphoenolpyruvate in islet B-cells stimulated with glucose.
B-cells stimulated with glucose showed enhanced activities of NADP-isocitrate dehydrogenase, aconitase, ATP-citrate lyase and phosphoenolpyruvate carboxy-kinase, elevated cytosolic [NADPH]/[NADP+] ratio, and increased concentrations of glucose 6-phosphate, 6-phosphogluconate, citrate, phosphoenolpyruvate and cytosolic free Ca2+. Phosphoenolpyruvate induced release of Ca2+ accumulated in isolated mitochondria. Glucose is suggested to stimulate a cytosolic NADP-linked dismutation and synthesis of citrate, associated with increased cytosolic free Ca2+ concentration. Subsequent breakdown of cytosolic citrate may yield Pi (possibly related to the "phosphate flush") and phosphoenolpyruvate which potentiates the release of Ca2+ accumulated in the B-cell mitochondria.
Boquist
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D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002951:Citrates / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000494:pharmacology*; D066298:In Vitro Techniques; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D051379:Mice; D008820:Mice, Obese; D009249:NADP / Q000378:metabolism*; D010728:Phosphoenolpyruvate / Q000378:metabolism*
D002951:Citrates; D009249:NADP; D010728:Phosphoenolpyruvate; D005947:Glucose; D002118:Calcium