模拟缺血-再灌注对窦房结细胞起搏离子流的影响及K_(ATP)通道开放剂的干预作用

探讨模拟缺血 再灌注对窦房结细胞起搏离子流 (If)的影响及KATP通道开放剂Pinacidil的干预效果。分离乳鼠窦房结细胞 ,纯化培养 2天后进行实验。随机分为对照组、模拟缺血 再灌注组 (I/R)、KATP通道开放剂Pinacidil干预组 (P +I/R)及KATP通道阻断剂 5 HD干预组 (5 HD +P +I/R及 5 HD +I/R)。采用常规全细胞膜片钳技术及多导管灌流系统 ,测定各组细胞If 密度 ,并绘制If 激活曲线。结果 :①每个窦房结细胞均可记录到If 电流 ,在相同指令电压下 ,I/R组窦房结细胞If 密度值较对照组明显增加 (P <0 .0 1) ;而P +I/R组则较I/R组显著减小 (P <0 .0 1) ;5 HD +P +I/R及 5 HD +I/R两组又较P +I/R组明显增加 (P <0 .0 1) ,但与I/R组比较无显著差异。②与对照组比较 ,I/R组窦房结细胞的If 激活曲线发生右移 ,半数最大激活电压由 - 10 8.0± 12 .4mV变为 - 89.5± 7.2mV(P <0 .0 1) ;P +I/R组窦房结细胞If 激活曲线较I/R组左移 ,半数最大激活电压为 - 99.5± 10 .8mV(P <0 .0 5 ) ;KATP通道阻断剂 5 HD可阻断Pinacidil对If 激活曲线的影响。结论 :KATP通道开放剂Pinacidil可对抗模拟缺血 再灌注对窦房结细胞If 的影响 ,此有利于维持模拟缺血 再灌注时窦房结细胞离子稳态和电生理活动的相对稳定

The Effects of Simulated Ischemia/Reperfusion on Hyperpolarazation-Actived Inward Current in Primary Cultured Neonatal Sinoatrial Node Cells and the Influence of ATP-Sensitive Potassium Channel Activator

To investigate the effects of simulated ischemia/reperfusion(I/R) on hyperpolarazation actived inward current(I f) in primary cultured neonatal sinoatrial node(SAN) cells and the influence of ATP sensitive potassium(K ATP ) channel activator,the SAN cells were isolated from newborn rats and purified and the 48 h cultured cells were cultivated in following mediums:simulated reperfusion solution as normal control,simulated ischemia/reperfusion solution(I/R),Pinacidil+I/R(P+I/R),5 HD+P+I/R and 5 HD+I/R.The ruptured patch whole cell technique and multiple superfusion lines were used to record the I f of SAN cells.The SAN cells used in experiments were verified by spontaneous action potentials recorded in current clamp mode(I=0).Results:I f could be recorded in all cells investigated.In the cells of I/R group,first current activation was observed at approximately -68 mV,and half maximal activation was -89.5±10.2 mV.Simulated ischemia/reperfusion led to a shift in current activation curves to more positive potentials with a increase in maximal current amplitude.Pinacidil caused the current activation curves of cells in I/R groups to more negative potentials,decreased the maximal current amplitude under the same commanding voltage.First current activation in I/R applied with Pinacidil was observed at approximately -77,half maximal activation was -99.5±10.8.5 HD reversed these effects of Pinacidil and itself had no appreciable effect on I f of cells.Conclusions:K ATP channel activator,pinacidil,makes current densities and activation curves of I f in I/R group approach normal levels,so it participates in maintaining ionic stability and electrophysiological stability of sinoatrial node cells during I/R.