UTP对猪冠状动脉平滑肌细胞BK_(Ca)通道作用机制的研究

目的:利用膜片钳技术,研究UTP对急性酶分离的猪冠状动脉平滑肌细胞上BKCa通道的作用,探讨生理条件下UTP调节BKCa通道的机制。方法:应用Cell-attached技术记录急性酶分离的猪冠状动脉平滑肌细胞上BKCa电流。用pCLAMP9.0软件系统进行数据采集及分析。结果:在Cell-attached膜片上,80μM UTP可明显激活BKCa通道(P0.05,n=21)。PLC抑制剂U73122可抑制UTP对BKCa的激活作用(P0.05,n=5)。PKC激动剂PMA(10nM),可使BKCa通道开放概率明显降低(P0.05,n=9)。UTP(80μM)预处理细胞之后,IP3抑制剂2APB(80μM),可使BKCa通道开放受抑(P0.05,n=6)。结论:在Cell-attached膜片上,UTP能激活猪冠脉平滑肌细胞BKCa通道。PLC信使转导通路中的IP3介导的胞内Ca2+释放是UTP激活BKCa通道的重要途径。

Regulation of UTP on BKCa channels of porcine coronary artery smooth muscle cells

Objective: To study the effect of UTP on BKCa channels in porcine coronary artery smooth muscle cells,and explore the regulatory mechanism under the physiological intracellular conditions.Methods: The coronary artery was excised from the heart of porcine.All experiments were done on single smooth muscle cells isolated enzymatically in symmetric high potassium solution and currents were recorded by patch clamp single channel recording technique.Single channel currents were amplified and filtered by patch clamp amplifier(CEZ-2300),then imported into the computer,pCLAMP9.0 software was used to record and analyze data.Results: In cell-attached patch,UTP(80 μM) enhanced BKCa channels open probability(Po) and reduced the mean close time(Tc)(n=21,P<0.01).In the presence of UTP,the specific blocker of phospholipase C-U73122(10 μM) decreased BKCa channels Po(n=5,P<0.05).Application of PKC activator PMA(10nM) obviously decreased BKCa channels Po(n=9,P<0.05).In the presence of UTP,2APB(80 μM) inhibited activation of BKCa channels mainly by suppressing BKCa channels Po(n=6,P<0.05).Conclusions: UTP could activate BKCa channels of porcine coronary ASMCs in cell-attached patches via signal transduction pathway.PLC/IP3 pathway was involved in UTP mediated BKCa channels,and played a prominent role in the activation of UTP on BKCa channels.