Acetylcholine increases voltage-activated Ca2+ current in freshly dissociated smooth muscle cells.
Acetylcholine increases voltage-activated Ca2+ current in freshly dissociated smooth muscle cells.
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乙酰胆碱可增加新分离的平滑肌细胞中电压激活的 Ca2 电流。
DOI：
10.1073/pnas.84.7.2092
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发表时间：
1987
影响因子：
11.1
通讯作者：
Singer,JJ
中科院分区：
文献类型：
--
作者：
Clapp,LH;Vivaudou,MB;WalshJr,JV;Singer,JJ
采用全细胞密闭记录技术，研究了乙酰胆碱对新鲜分离的中华大蟾胃平滑肌细胞电压激活钙电流的调节作用。在内源性Cs+存在的情况下，正向指令脉冲从-80 mV附近激发出钙电流，以阻断外向K+电流。当指令电位接近10 mV时，钙电流最大。在这样的指令电位下，乙酰胆碱增加了内向电流的幅度，并减缓了它的衰减。在无外源性Na+或低氯离子(天冬氨酸取代物)的条件下，乙酰胆碱的作用与毒扁豆碱相似。乙酰胆碱不能使钙电流的电流-电压关系峰明显沿电压轴移动。这些结果表明，M受体的激活不仅抑制K+电流(M-电流)，正如我们以前所证明的那样[Sims，S.M.，Singer，J.J.&Walsh，J.V.，Jr.(1985)J.Physiol。(London)367,503-529]，但也增加了钙电流的幅度，减缓了钙电流的衰减。
The regulation of voltage-activated Ca2+ current by acetylcholine was studied in single freshly dissociated smooth muscle cells from the stomach of the toad Bufo marinus by using the tight-seal whole-cell recording technique. Ca2+ currents were elicited by positive-going command pulses from a holding level near -80 mV in the presence of internal Cs+ to block outward K+ currents. Ca2+ current was greatest in magnitude at command potentials near 10 mV. At such command potentials, acetylcholine increased the magnitude of the inward current and slowed its decay. The effects of acetylcholine were seen in the absence of external Na+ or with low Cl- (aspartate replacement) in the bathing solution and could be mimicked by muscarine. The peak of the current-voltage relationship for the Ca2+ current was not discernibly shifted along the voltage axis by acetylcholine. These results demonstrate that activation of muscarinic receptors not only suppresses a K+ current (M-current), as we have previously demonstrated [Sims, S. M., Singer, J. J. & Walsh, J. V., Jr. (1985) J. Physiol. (London) 367, 503-529], but also increases the magnitude and slows the decay of Ca2+ current.