Physiological roles of the calcium wave for the regulation of fluid and electrolytes secretion in salivary cells

1.钙信号引起的细胞收缩和氯化物分泌：(1)在腮腺细胞顶端观察到0.1-0.25um氨基甲胆碱引起的钙振荡。钙振荡以波的形式向基底区扩散，并导致缓慢收缩。(2)0.5um氨基甲酰胆碱引起瞬间钙波，并在到达基底区约1秒后迅速收缩。(3)0.5um卡巴胆碱也引起快速的氯离子分泌，其时间过程与收缩相似。(4)洛诺霉素在基底区引起大量的钙反应并引起缓慢的收缩。这些结果表明，根尖区的钙反应对诱导液体和电解质的分泌特别重要。检测大鼠腮腺细胞的AQP亚型。Western印迹证实AQP-5在细胞类型中表达。3.递增激动剂刺激下的钙波。(1)用多光子激光显微镜观察细胞内功能的钙库。(2)亚最大浓度1P3对细胞内钙释放和摄取的影响表明，细胞内钙离子浓度的降低抑制了IP3受体的功能。本研究阐明唾液细胞中的钙调节系统维持钙反应的时空模式，并允许从尖端启动钙反应。推测最适的唾液分泌是由这种钙信号诱导的。

1. Cell shrinkage and chloride secretion induced by calcium signal.(1) Calcium oscillation by the application of 0.1-0.25 uM carbachol was observed at the apical region of parotid cells. The calcium oscillation spreaded as a wave toward the basal area and induced a slow shrinkage.(2) 0.5 uM carbachol elicited a transient calcium wave and a rapid shrinkage after ~1 sec after reaching the calcium wave to the basal area.(3) 0.5 uM carbachol also elicited a rapid chloride secretion with a similar time course as the shrinkage.(4) lonomycin induced a large calcium response at the basal area and caused a slow shrinkage.These results suggest that the calcium response at the apical area is particularly important to induced fluid and electrolytes secretions.2. Examination of AQP subtype in rat parotid cells.Western blot confirmed the AQP-5 is expressed in the cell type.3.Calcium wave with incremental agonist stimulations.(1) We visualized the functional intracellular calcium stores with multi-photon laser microscopy. In addition, the photobleaching assay revealed that calcium stores at the apical and basal area are continuous.(2) Effects of submaximal concentrations of 1P3 on the calcium release and uptake indicate that the function of IP_3 receptors is suppressed by the decrease in calcium concentrations within the store.The present study clarified that calcium-regulating system in salivary cells act to maintain the spatiotemporal pattern of calcium response, and allowed to initiated it from the apical area. It is speculated that the optima I salivary secretion is induced with this patterned calcium signal.