Karl R C, Zawalich W S, Ferrendelli J A, Matschinsky F M
J Biol Chem. 1975 Jun 25;250(12):4575-9.
Insulin release from isolated perifused pancreatic islets was stimulated by the divalent ionophore A23187 in the absence of exogenous glucose. In addition, A23187 produced a 2-fold elevation of cyclic adenosine 3':5'-monophosphate (cAMP) levels in isolated perifused islets. The elevation of cAMP levels coincided with peak insulin release. Ionophore-induced insulin release was unaffected by pretreatment of the islets with theophylline (5 mM). Stimulation of insulin release produced by the ionophore occurred either in the presence or absence of extracellular Ca-2+; however, cAMP accumulation required the presence of extracellular Ca-2+. The ionophore (10 muM) had no effect on adenylate cyclase activity of homogenates of isolated islets. The results of this study are interpreted as indicating that intracellular Ca-2+ has an essential role in the insulin releasing mechanism, whereas the cAMP system has a modulatory effect on this process.
在没有外源性葡萄糖的情况下，二价离子载体A23187刺激了分离的经灌流胰岛释放胰岛素。此外，A23187使分离的经灌流胰岛中的环磷酸腺苷（cAMP）水平升高了2倍。cAMP水平的升高与胰岛素释放峰值同时出现。离子载体诱导的胰岛素释放不受用茶碱（5 mM）预处理胰岛的影响。离子载体产生的胰岛素释放刺激在细胞外Ca2+存在或不存在的情况下均会发生；然而，cAMP积累需要细胞外Ca2+的存在。离子载体（10 μM）对分离胰岛匀浆的腺苷酸环化酶活性没有影响。本研究结果被解释为表明细胞内Ca2+在胰岛素释放机制中起关键作用，而cAMP系统对这一过程具有调节作用。
