Hansen M, Boitano S, Dirksen E R, Sanderson M J
Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark.
J Cell Sci. 1995 Jul;108 ( Pt 7):2583-90. doi: 10.1242/jcs.108.7.2583.
Mechanical stimulation of a single cell in an airway epithelial culture initiates an increase in intracellular Ca2+ concentration ([Ca2+]i) that propagates from cell to cell as an intercellular Ca2+ wave. These Ca2+ waves appear to require an increase in intracellular inositol 1,4,5-trisphosphate (IP3) concentration ([IP3]i) in the stimulated cell and are propagated between cells by the diffusion of IP3 through gap junctions. To test the hypothesis that the activation of phospholipase C (PLC) contributes to the elevation of [IP3]i and initiation of an intercellular Ca2+ wave, changes in [Ca2+]i induced by mechanical stimulation were measured by digital fluorescence microscopy in the presence of the PLC inhibitor, aminosteroid U73122. Following exposure to U73122 mechanical stimulation elevated [Ca2+]i of the stimulated cell, but did not initiate the propagation of an intercellular Ca2+ wave. By contrast, in the presence of U73343, a similar aminosteroid that does not inactivate PLC, mechanical stimulation increased the [Ca2+]i of the stimulated cell and initiated an intercellular Ca2+ wave. U73122 also blocked the elevation of [Ca2+]i of airway epithelial cells in response to ATP, a P2-receptor agonist that activates PLC to elevate [IP3]i and [Ca2+]i. In addition, the propagation of intercellular Ca2+ waves was not affected by the ryanodine-receptor agonists, caffeine or ryanodine. The hypotheses that: (1) an elevation of [IP3]i is required to initiate intercellular Ca2+ waves; (2) mechanical stimulation activates PLC; and (3) Ca2+ wave propagation in airway epithelial cells involves Ca2+ release from intracellular stores primarily via IP3 receptors are supported by these results.
对气道上皮细胞培养物中的单个细胞进行机械刺激，会引发细胞内钙离子浓度（[Ca2+]i）升高，该升高会以细胞间钙离子波的形式在细胞间传播。这些钙离子波似乎需要受刺激细胞内的肌醇1,4,5-三磷酸（IP3）浓度（[IP3]i）升高，并且通过IP3经缝隙连接的扩散在细胞间传播。为了验证磷脂酶C（PLC）的激活有助于[IP3]i升高和细胞间钙离子波起始这一假说，在存在PLC抑制剂氨基类固醇U73122的情况下，通过数字荧光显微镜测量机械刺激诱导的[Ca2+]i变化。暴露于U73122后，机械刺激使受刺激细胞的[Ca2+]i升高，但未引发细胞间钙离子波的传播。相比之下，在存在U73343（一种不会使PLC失活的类似氨基类固醇）的情况下，机械刺激增加了受刺激细胞的[Ca2+]i并引发了细胞间钙离子波。U73122还阻断了气道上皮细胞对ATP（一种激活PLC以升高[IP3]i和[Ca2+]i的P2受体激动剂）的反应中[Ca2+]i的升高。此外，细胞间钙离子波的传播不受ryanodine受体激动剂咖啡因或ryanodine的影响。这些结果支持了以下假说：（1）细胞间钙离子波的起始需要[IP3]i升高；（2）机械刺激激活PLC；（3）气道上皮细胞中钙离子波的传播主要涉及通过IP3受体从细胞内储存库释放钙离子。
