Cellular calcium regulates outward currents in rabbit intestinal smooth muscle cell.
Cellular calcium regulates outward currents in rabbit intestinal smooth muscle cell.
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细胞钙调节兔肠平滑肌细胞的外向电流。
DOI：
10.1152/ajpcell.1987.252.4.c401
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
H. Kuriyama
中科院分区：
文献类型：
--
作者：
Y. Ohya;K. Kitamura;H. Kuriyama
采用单电极电压钳技术，研究了兔回肠纵肌层碎片状平滑肌细胞（平滑肌球，SMB）瞬态和振荡向外电流（ITO和IOO）的性质。移液管中加入含有0.3 mM乙基氨基乙醚-N，N'-四乙酸（EGTA）的高K+溶液，浴液中加入生理盐溶液（PSS），在Ca向内电流后产生大的瞬态向外电流（ITO），在持续向外电流（ISO）上产生正向至-30 mV（保持电位-60 mV）的向外电流（IOO）自发振荡。当用Cs+-四乙基铵+ (TEA+)溶液替代SMB的内部液体，或使用细胞内灌注技术将移液管中EGTA的浓度增加到4 mM时，ITO和IOO均被消除。在Mn2+溶液中，这两种电流也被抑制。浴液应用TEA+、普鲁卡因或A23187完全阻断ITO和IOO。咖啡因（0.3-1 mM）增强了ITO的振幅和IOO的世代，浓度超过3 mM的咖啡因短暂增强，但最终抑制了这两种电流。这些结果表明，ITO的产生与Ca2+内流密切相关，而IOO的产生可能是由细胞内Ca2+浓度的增加引起的，可能是从储存部位释放的。
The nature of transient and oscillatory outward currents (ITO and IOO) in fragmented smooth muscle cells (smooth muscle ball, SMB) from the longitudinal muscle layer of the rabbit ileum, was studied using a single electrode voltage clamp technique. With a high K+ solution containing 0.3 mM ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid (EGTA) in the pipette and physiological salt solution (PSS) in the bath, the Ca inward current was followed by a large transient outward current (ITO) and spontaneous oscillations of the outward current (IOO) on the sustained outward current (ISO) were elicited by a depolarizing pulse, positive to -30 mV (holding potential of -60 mV). When the internal fluid of the SMB was replaced with Cs+-tetraethylammonium+ (TEA+) solution, or when the concentration of EGTA in the pipette was increased to 4 mM, using the intracellular perfusion technique, both ITO and IOO were abolished. In Mn2+ solution both currents were also inhibited. Bath application of TEA+, procaine or A23187 completely blocked both ITO and IOO. Caffeine (0.3-1 mM) enhanced the amplitude of ITO and generations of IOO, and concentrations of caffeine over 3 mM transiently enhanced, but finally suppressed both these currents. These results suggest that the generation of ITO is closely related to the Ca2+ influx, whereas the generation of IOO may be initiated by an increment in the intracellular concentration of Ca2+, possibly released from store sites.