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The stimulus-secretion coupling of glucose-induced insulin release: IL. Thiol : disulfide balance in pancreatic islets

par Anjaneyulu, Kowluru;Anjaneyulu, Renu;Sener, Abdullah ;Malaisse, Willy
Référence Biochimie, 64, page (29-36)
Publication Publié, 1982

Article révisé par les pairs

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Résumé :

An increase in the production rate of reduced pyridine nucleotides is currently considered as a coupling factor between metabolic and distal events in the process of glucose-stimulated insulin release. The possible participation in such a coupling of thiol: disulfide interchanges was investigated in rat pancreatic islets. NADPH-dependent glutathione reductase and glutathione-cystine transhydrogenase activities were present in islet homogenates, whereas no glutathione peroxidase activity could be detected. In intact islets, glucose (16.7 mM) augmented both the GSH/GSSG ratio (from a basal value of 6.7 ± 0.6 to 8.4 ± 0.4) and the tissue content of sulphydryl groups (from a basal value of 119 ± 7 to 170 ± 9 pmol/μg protein). The latter effect was mimicked by d-glyceraldehyde, 2-ketoisocaproate, anoxia and KCN; it failed to be reproduced by l-glucose or d-fructose, was unaffected by theophylline, and was inhibited by d-mannoheptulose, iodoacetate, menadione, cytochalasin B and the absence of extracellular Ca2+. These findings support the view that a glucose-induced reduction of disulphide bridges to sulphydryl groups participates in the stimulus-secretion coupling of nutrient-induced insulin release. © 1981 Masson, Paris.