Glutathione potentiates glucose- stimulated insulin secretion in isolated porcine islets
Islets freshly isolated from higher mammals suffer oxidative stress which may reduce their function. Glutathione (GSH) is a cellular antioxidant which reduces oxidative stress in animal systems. Therefore, the AIM of the present study was to determine if GSH pretreatment of isolated porcine islets enhances in vitro response to glucose. METHODS: Nine female pigs (25-30 kg) were anesthetized and exsanginated. Rapid celiotomy and pancreatectomy were performed. Islets were isolated by a modified Ricordi technique, and 10 islets per experiment were handpicked for preperifusion with Kreb's Ringer-Bicarbonate solution (KRB) containing 1 albumin and 5.5 mM (basal) glucose with or without 10 mM GSH. After preperifusion, basal samples were collected for 20 min. Islets were then perifused with KRB containing 27.7 mM glucose alone for 30 min, before returning to a 20-min basal perifusion with sample collection. Samples were collected on ice every 2 min and stored frozen until radioimmunoassay for insulin. RESULTS: Under basal conditions, untreated islets had a mean rate of insulin secretion of 1315.7±97.8 pg/min and did not respond to glucose. In contrast, islets treated with GSH had a lower basal insulin secretion: 246.7±97.8 pg/min (p<0.001 vs untreated islets), which rose to 1896 ± 108.3 pg/min (p<0.001) with a normal biphasic response when stimulated with glucose. CONCLUSION: GSH enhances pancreatic islet function in vitro. In vivo experiments with transplanted GSH-pretreated islets are warranted.
Garfinkel, MR; Yadav, SS; Harland, RC; Hatchell, DL; Opara, EC
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