AIM To explore the cellular mechanisms in which prostaglandin F_ 2α (PGF_ 2α ) augments glucose stimulated insulin secretion
in NIT-1β cells. METHODS Insulin content in supernatant was measured by radioimmunoassay. Intracellular calcium concentration (
_i) of NIT-1β cells was determined by confocal laser scanning method with Fluo-3/AM as a fluorescent probe. RESULTS In the presence of 16.5 mmol·L -1 glucose, 5 μmol·L -1 PGF_ 2α or 20 mmol·L -1 tetraethylammonium (TEA, a potassium channel blocker) both increased significantly insulin secretion, while combination of TEA and PGF_ 2α could not induce more elevation in insulin secretion. In the presence of 5.5 mmol·L -1 glucose, PGF_ 2α did not increase insulin secretion. But when pretreated with TEA, PGF_ 2α significantly enhanced insulin secretion stimulated by 5.5 mmol·L -1 glucose. PGF_ 2α did not potentiate insulin secretion stimulated by 16.5 mmol·L -1 glucose when NIT-1β cells were in depolarized condition in the presence of 60 mmol·L -1 KCl and 250 μmol·L -1 diazoxide or pretreated with chloride channel blocker 4,4′- diisothiocyanatostilbene -2,2′-disulfonic acid(DIDS). Otherwise, PGF_ 2α significantly elevated NIT-1β cells _i, but pretreated with 60 mmol·L -1 KCl and 250 μmol·L -1 diazoxide, the effect was canceled. DIDS not only decreased significantly _i of NIT-1β cells, but also reversed the effect of PGF_ 2α from increasing _i to decreasing _i. CONCLUSION Potentiation of PGF_ 2α on the glucose-induced insulin secretion may be mediated by membrane depolarization through activation of chloride channels and elevation of _i.