模拟缺血对培养乳鼠窦房结细胞膜K_(ATP)通道电流的影响

Effect of simulated ischemia on current of K_(ATP) channel in cultured sinoatrial node cells in neonatal rats

目的观察模拟缺血对原代培养乳鼠窦房结细胞膜KATP通道电流的影响,为保护缺血窦房结细胞提供实验依据。方法取培养2d乳鼠窦房结细胞进行实验,将细胞放入灌流槽,用模拟缺血液持续灌流,并在不同阶段加入KATP通道阻断剂Glibenclamide(10μM/L),采用全细胞膜片钳技术,在钳制电压为-40mV情况下连续纪录的跨膜电流的变化情况。结果在-40mV钳制电压下,窦房结细胞模拟缺血2min可产生KATP通道外向电流,该电流5min左右达最大值,约10min后自行衰减。在细胞外液中加入Glibenclamide后,模拟缺血诱发的跨膜外向电流明显减小〔(7.5±0.8)pA vs(2.1±0.3)pA,P<0.05〕。Glib-enclamide可加速模拟缺血诱导的外向电流的衰减,它对电流的阻断率为68.5%〔(2.4±0.4)pA vs(7.5±0.8)pA,P<0.05〕。结论模拟缺血可引起窦房结细胞膜上对Glibenclamide敏感的KATP通道的开放,这可能有利于保护缺血窦房结细胞。

Objective To study the currents of KATP ehannels（IK（ATP）） in primary cultured sinoatrial node（SAN） cells in neonatal rats during simulated ischemia, and to provide the protective experiment basis for ischemic SAN cells. Methods The SAN cells were isolated from newborn rats and purified. The 48h cultured cells were cultivated in simulated isehemic solution which was presented the blockers of KATP channel Glibenclamide（10μM/L） at differ phases. The ruptured-patch whole-cell technique and multiple superfusion lines were used to record the IK（ATP） of SAN cells（HP=-40mV）. The SAN cells used in experiments were verified by spontaneous action potentials recorded in current-clamp mode（I=0）. Results Under the holding potential of -40mV,2min simulated ischemia induced the currents of KATP channels in SAN cells. The currents arrived to its peak about at 5min and it was run-down after 10min. Adding the Glibenclamide in advance, the currents induced by simulated isehemia significantly reduced[（7.5±0. 8）pA vs （2.1 ±0.3 ）pA,P〈0.05]. Glibenclamide could accelerate the process of run-down, the ratio of current interdiction was 68.5% [（2.4±0.4）pA vs （7.5±0.8）pA,P〈0.05]. Conclusion Simulated ischemia induce the opening of KATp channels in the membrane of SAN cells and it may be propitious to the protection of ischemic SAN cells.