Calcium channel alterations coupled with secretory response in rat parotid gland cells

众所周知，钙离子在细胞的生理功能调节中起着重要作用。在唾液腺中，钙离子激活细胞内过程并引起分泌反应。钙通道被认为是调节细胞内钙离子浓度的重要因素。我们研究了与分泌反应有关的大鼠腮腺细胞的钙通道特性。大鼠腮腺细胞在含钙离子载体A23187的培养液中或在含K~(2+)的培养液中孵育，可分泌淀粉酶。异丙肾上腺素刺激大鼠腮腺细胞的β-肾上腺素受体或乙酰胆碱，也可引起细胞分泌淀粉酶。适当浓度的胞外钙是大鼠腮腺细胞分泌淀粉酶所必需的。…中分泌颗粒--酵素颗粒中淀粉酶的释放更多的大鼠腮腺细胞也受到低浓度钙的调节。大鼠腮腺分散细胞与乙酰胆碱孵育5min后，肌醇1，4，5-三磷酸含量增加约80%。在37ﾟ℃下，这些结果表明，从腮腺细胞内储存的钙离子对淀粉酶的分泌有刺激作用。硝苯地平、尼卡地平、维拉帕米或地尔硫卓不能阻断乙酰胆碱或异丙肾上腺素引起的大鼠腮腺细胞淀粉酶分泌。尼群地平与大鼠腮腺细胞膜的结合实验没有发现特异性结合部位，说明细胞内钙离子浓度的增加是通过药物受体激活的钙通道进入细胞内，并被1，4，5-三磷酸肌醇释放出来，在细胞淀粉酶的分泌过程中起重要作用。较少

It is well known that calcium ion plays an important for role in the regulation of the physiological function of cells. In salivary glands, calcium ion activates the intracellular processes and causes the secretory response. Calcium channel is considered to be very important to regulate the intracellular calcium concentration. We have studied characteristics of the calcium channel in rat parotid ,land cell in relation to secretory response.Amylase was secreted from rat parotid gland cells by the incubation oil them in the medium containing a calcium ionophore, A23187, or in the medium containing high concentration of K^+. The stimulation by isoproterenol of beta-adrenoceptors or acetylcholine of muscarinic receptors of rat parotid gland cells caused also amylase secretion from the cells. The presence of an adequate concentration of extracellular calcium was necessary for the amylase secretion from rat parotid gland cells. Release of amylase from secretory granules, zymogen granules, in … More rat parotid gland cells was also regulated by a low concentration of calcium. The contents of inositol 1, 4, 5-triphosphate in rat parotid gland dispersed cells were increased about 80% by the incubation of them in the presence of acetylcholine for 5 min. at 37ﾟC. These results showed that calcium ion liberated from an intracellular store of parotid gland cells has a stimulatory effect on amylase secretion. Amylase secretion from rat parotid gland cells caused by acetylcholine or isoproterenoll was not blocked by nifedipine, nicardipine, verapamil, or diltiazem. Binding experiments of [^3H]nitrendipine with rat parotid gland cell membrane did not show the presence of specific binding sites.These results clarify that the increases in the intracellular concentration of calcium ion entered into rat parotid gland cells through the calcium channel activated by drug receptors and liberated from an intracellular store in the cells by inositol 1, 4, 5-triphosphate play an important role in amylase secretion from the cells. Less