Molecular mechanism of the receptor-mediated Ca^<2+> entry in parotid cells

1)蛋白激酶抑制剂星形孢菌素对大鼠腮腺细胞容量性钙内流的影响。2)丝氨酸/苏氨酸磷酸酶抑制剂对大鼠腮腺细胞容积性钙内流的影响。3)ATP诱导大鼠腮腺细胞内钙离子内流。这些结果提示，大鼠腮腺细胞的钙离子内流可能受蛋白磷酸化/去磷酸化的调节。胞外ATP可增加胞内Ca~(2+)~(2+)浓度，而不形成肌醇磷酸。这一增加似乎是由于钙离子通过激活P_2Z&gt；嘌呤受体进入细胞内。4)细胞内钙离子在大鼠腮腺腺泡细胞内动员的成像。用卡巴胆碱刺激腮腺腺泡细胞，细胞顶端的胞浆Ca~(2+)~(2+)和Gt~(2+)开始升高。此后，这种增长蔓延到了基底外侧地区。当细胞内钙离子储备耗尽后加入培养液中，基极细胞内钙离子储备增加。5)人腮腺导管细胞系细胞内钙离子储备的可视化。用激光共聚焦显微镜的数字成像技术显示细胞内的钙离子储存。结果表明，整个内质网和核膜是IP_3敏感的Ca~(2+)&gt；

1) Effects of the protein kinase inhibitor staurosporine on capacitative Ca^<2+> entry in rat parotid cells. Staurosporine significantly enhanced Ca^<2+> entry from extracellular medium activated by depletion of intracellular Ca^<2+> stores.2) Effects of serine/threonine phosphatase inhibitors on capacitative Ca^<2+> entry in rat parotid cells. The phosphatase inhibitors (calyculin-A, tautomycin, okadaic acid) suppressed the Ca^<2+> entry induced by depletion of intracellular Ca^<2+> stores.These results suggest that the capacitative Ca^<2+> entry may be regulated by protein phosphorylation/dephosphorylation.3) ATP-induced Ca^<2+> entry in rat parotid cells. Ectracellular ATP increased cytosolic Ca^<2+> concentration without formation of inositol phosphates. This increase appears to be due to an entry of Ca^<2+> via activation of P_<2Z> purinoceptors.4) Imaging of intracellular Ca^<2+> mobilizing in rat parotid acinar cells. When parotid acinus was stimulated with carbachol, the initial rise in cytosolic Ca^<2+> was detected in the apical pole of the cells. Thereafter, the increase spreaded into the basolateral area. When Ca^<2+> was added to the medium following depletion of intracellular Ca^<2+> stores, an increase in cytosolic Ca^<2+> was observed in the basal pole.5) Visualization of intracellular Ca^<2+> stores in a human parotid ductal cell line. The intracellular Ca^<2+> stores were visualized using digital imaging techniques with a confocal laser microscopy. The results demonstrate that the entire ER and the nuclear envelop serve as IP_3-sensitive Ca^<2+> stores.