【摘要】 目的探讨前列腺素F2α(PGF2α)促进NIT-1β细胞葡萄糖刺激性胰岛素分泌的作用机制。方法放射免疫法检测NIT-1β细胞胰岛素分泌量;激光共聚焦显微镜检测细胞[Ca2+]i。结果葡萄糖浓度为16.5mmol·L-1时,PGF2α5μmo·lL-1或钾通道阻断剂四乙胺(TEA)20mmol·L-1均使NIT-1β细胞胰岛素分泌明显增加,而先给予TEA后再加PGF2α或先给PGF2α再加TEA均不能使胰岛素分泌进一步增加。葡萄糖浓度为5.5mmol·L-1时,PGF2α不能使胰岛素分泌增加,预先给予20mmol·L-1TEA再应用PGF2α,胰岛素分泌显著增加。60mmol·L-1KCl和250μmol·L-1二氮嗪使细胞膜处于最大去极化状态时,PGF2α不能促进胰岛素分泌。16.5mmol·L-1葡萄糖浓度下,预先给予氯通道阻断剂4,4′-二异硫氰酸水合茋-2,2′-二磺酸(DIDS),PGF2α不能促进胰岛素分泌。另外,16.5mmol·L-1葡萄糖下,5μmol·L-1PGF2α引起NIT-1β细胞[Ca2+]i升高,而预先给予60mmol·L-1KCl和250μmo·lL-1二氮嗪后再给予PGF2α不能引起细胞[Ca2+]i升高;在DIDS作用下,NIT-1β细胞[Ca2+]i显著降低,恢复静息期后给予PGF2α,细胞[Ca2+]i再次降低。结论促进细胞膜去极化在PGF2α增强胰岛素分泌中起着重要作用。PGF2α可能通过激活氯通道,增强NIT-1β细胞膜去极化,升高细胞[Ca2+]i,促进高浓度葡萄糖刺激下的胰岛素分泌。更多还原

【Abstract】 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 （[Ca 2+ ]_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 [Ca 2+ ]_i, but pretreated with 60 mmol·L -1 KCl and 250 μmol·L -1 diazoxide, the effect was canceled. DIDS not only decreased significantly [Ca 2+ ]_i of NIT-1β cells, but also reversed the effect of PGF 2α from increasing [Ca 2+ ]_i to decreasing [Ca 2+ ]_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 [Ca²⁺]_i.更多还原