Role of cyclic AMP and Ca^<2+> in priming and fusion/exocytosis of parotid amylase secretion

将大鼠腮腺腺泡细胞灌流于柱中，以检测cAMP和Ca^2+在淀粉酶分泌的启动和融合/胞吐中的作用。卡巴胆碱（Cch）引起的双相反应的淀粉酶分泌与初始快速，大的峰值和随后的持续高原。异丙肾上腺素产生缓慢增加淀粉酶分泌，并达到比Cch诱导的更大的平台。联合刺激异丙肾上腺素和Cch大大增强淀粉酶分泌。联合刺激诱导的淀粉酶分泌的上升和下降与单独由Cch诱导的那些相似，但不是由异丙肾上腺素诱导的，这表明增强是由异丙肾上腺素诱导的Cch效应的修饰引起的。Cch诱导的淀粉酶分泌的浓度反应与异丙肾上腺素和无异丙肾上腺素显示，异丙肾上腺素大大提高了Cch的敏感性和最大效果的效果。当Ca^<2+>效应消失时， ...更多信息 在用离子霉素代替Cch渗透Ca^2+的细胞中进行了检测。在无Ca^2+培养基中，Cch仅引起淀粉酶分泌的起始峰，但不产生持续的平台期，异丙肾上腺素不增强Cch对[CA^2+]的作用，2，4-二硝基苯酚和羰基氰间氯苯腙不降低Cch诱导的淀粉酶分泌的起始峰，但显著降低异丙肾上腺素和Cch诱导的持续反应。这些结果表明，Cch通过Ca^<2+>对淀粉酶分泌有两种不同的作用：触发融合/胞吐和启动分泌颗粒。异丙肾上腺素通过环腺苷酸也有两种不同的作用：直接刺激启动和增强对Ca^2+效应的敏感性。因此，异丙肾上腺素通过增加分泌颗粒的启动池来刺激淀粉酶分泌，这是Ca^2+效应的结果。因此，异丙肾上腺素刺激淀粉酶的分泌，通过增加引发池的分泌颗粒，而Cch增加流量的分泌颗粒进入/从引发池，这是大大增强了异丙肾上腺素。少

Rat parotid acinar cells were perfused in the column to examine the role of cAMP and Ca^<2+> in the priming and fusion/exocytosis of amylase secretion. Carbachol (Cch) evoked a biphasic response of amylase secretion with an initial rapid, large peak and a subsequent sustained plateau. Isoproterenol produced slowly increasing amylase secretion and reached the plateau that was larger than that induced by Cch. Combined stimulation with isoproterenol and Cch greatly potentiated amylase secretion. The rise and decay of amylase secretion induced by the combined stimulation were similar to those induced by Cch alone but not by isoproterenol suggesting that the potentiation is caused by isoproterenol-induced modification of the Cch effect. Concentration-responses of Cch-induced amylase secretion with and without isoproterenol showed that isoproterenol largely enhances the effect of Cch in both the sensitivity and maximum effect. Similar potentiation was observed when the Ca^<2+> effect was dir … More ectly examined in cells permeabilized to Ca^<2+> with ionomycin instead of Cch. In a Ca^<2+> -free medium, Cch evoked only an initial peak, but did not produce a sustained plateau, Isoproterenol did not enhance the effect of Cch on [CA^<2+>] 2,4-Dintrophenol and carbonyl cyanide m-chlorophenyl hydrazone did not decrease the Cch-induced initial peak of amylase secretion, but markedly decreased the sustained responses induced by isoproterenol and Cch. These results suggest that Cch, via Ca^<2+>, has two distinct effects on amylase secretion ; triggering of fusion/exocytosis and priming of secretory granule. Isoproterenol, via cyclic AMP, also has two distinct effects ; direct stimulation of priming and enhancement of the sensitivity to the Ca^<2+> effects. Thus, isoproterenol stimulates amylase secretion by increasing the primed pools of secretory granules, to the Ca^<2+> effects. Thus, isoproterenol stimulates amylase secretion by increasing the primed pools of secretory granules, whereas Cch increases the flux of secretory granules into/from the primed pools, which is greatly enhanced by isoproterenol. Less