三磷酸肌醇对猪冠状动脉平滑肌细胞大电导钙激活钾通道的.pdfVIP

生理学报 Acta Physiologica Sinica, June 25, 2005, 57 (3): 303-309 303 研究论文 三磷酸肌醇对猪冠状动脉平滑肌细胞大电导钙激活钾通道的 作用 蔡 芳， 曾晓荣，杨 艳 *，刘智飞，李妙龄，周 文，裴 杰 泸州医学院心肌电生理学研究室，泸州 646000 摘 要：应用膜片钳单通道电流记录技术，研究三磷酸肌醇( trisphosphate inositol, IP3 ) 对猪冠状动脉平滑肌细胞大电导钙 2+ 激活钾通道( large-conductance Ca -activated potassium channels, BK channels ) 的作用。结果显示：在内面向外式(inside-out) 膜片下，IP3 (10~50 μmol/L)可以浓度依赖性地增加通道的开放概率，而对电流幅值无明显影响，开放概率的增加是通过 明显缩短平均关闭时间实现的(n=11, P0.01) ；洗去药物后通道活性可以恢复到对照水平；IP3 对通道的激活作用不随时间 而衰减；IP3 的降解产物对通道没有明显的激活作用。结果表明：在 inside-out 膜片下，IP3 能够激活猪冠状动脉平滑肌细 胞 BK 通道。 关键词：大电导钙激活钾通道；1,4,5- 三磷酸肌醇；冠状动脉；平滑肌细胞；膜片钳技术 中图分类号：Q463; R331.3+8 Effect of IP3 on BK channels of porcine coronary artery smooth muscle cells CAI Fang, ZENG Xiao-Rong, YANG Yan*, LIU Zhi-Fei, LI Miao-Ling, ZHOU Wen, PEI Jie Institute of Myocardial Electrophysiology, Luzhou Medical College, Luzhou 646000, China 2 ＋ Abstract: D-myo-inositol 1,4,5-trisphosphate (IP3) plays an important role in signal transduction. It releases Ca from intracellular sites, which activates the Ca2 ＋ -dependent channels such as large-conductance Ca2+-activated potassium channels (BK channels). The present study was therefore designed to determine if the activity of BK channels in porcine coronary artery smooth muscle cells was increased by IP3. Using the inside-out patch-clamp technique, the activity of single BK channels was recorded in porcine coronary artery smooth muscle cells. In excised inside-out membrane patches, IP3 (10~50 μmol/L) enhanced the open probability (Po) of BK channels in a dose-dependent manner in the intracellular side of inside-out patches and its effect was almost completely abolished by washout.