ATP sensitive K^+ channel may be involved in the protective effects of preconditioning in isolated guinea pig cardiomyocytes

ATP敏感性钾通道可能参与对经预处理的离体豚鼠心肌细胞的保护作用(英文)

Objective To develop a cellular model of preconditioning by a brief period of hypoxia in isolated guinea pig cardiomyocytes and to determine whether or not an ATP sensitive K+ (KATP) channel is involved in ischemic preconditioning. Methods Single myocytes were isolated from the ventricle of adult guinea pigs. The experimental chamber allowed the cells to be exposed to low O2 pressure. During hypoxic preconditioning, the cells were equilibrated with normaxic solution for 10 minutes and then exposed to hypoxia for 5 minutes, followed by 10 minutes of reoxygenation. The cells were then subjected to 20-180 minutes of hypoxia and reoxygenation. Ionic currents were studied with the patch clamp technique in whole-cell and cell-attached configurations. Results A 5-minute hypoxic preconditioning offered a significant protection from cell injury in subsequent hypoxia-reoxygenation. After a latency of more than 15 minutes, hypoxia induced a time-independent outward K+ current which could be blocked by 5?μmol/L glibenclamide. At 10?mV, the current increased from 78±15?pA to 1581±153?pA (P<0.01, n=18). However, the latency to develop KATP channel currents (IKATP) was greatly shortened in preconditioned cells, and the current was increased acceleratively. At 10?mV, the current more than 4?nA was recorded in preconditioning cells. In the single channel recordings, the time interval from the first channel opening to maximum opening was also markedly abbreviated in preconditioned cells. Conclusion Isolated guinea pig cardiomyocytes can be preconditioned with a brief period of hypoxia. This hypoxic preconditioning may modify the KATP channel, and make the channel open more readily during the second hypoxia.

目的 对离体豚鼠心肌细胞予以短时间的低氧建立细胞预处理模型 ,并以此判定ATP敏感性钾通道是否参与此缺氧 (模拟缺血 )的预处理。方法 从成年豚鼠的心室分离出单个心肌细胞 ,进行实验的灌流槽容许这些细胞暴露于低氧灌流液从而处于低氧分压状态。在低氧预处理过程中 ,细胞先在正常溶液中平衡 10分钟然后暴露于低氧灌流液中 5分钟 ,随后给予 10分钟的复氧。对这些经预处理的细胞给予低氧 2 0 - 180分钟并再复氧。用斑片钳技术进行全细胞和单通道记录研究其离子流变化。结果 5分钟的低氧预处理可对细胞低氧复氧所引起的损伤提供显著的保护作用。经 15分钟以上的延迟后 ,低氧诱导出非时间依赖性的钾外流 ,此外向性电流可被 5μmol/L的格列本脲所阻断。在除极化至 10mV时 ,此电流从 78± 15pA增至 1581± 153pA(P <0 0 1,n =18)。然而 ,产生ATP敏感性钾通道电流的延迟时间在经预处理的细胞中大为缩短 ,并增高更快。在 10mV时超过 4nA。在单通道记录中 ,从第一个通道开放到最大开放的时距在预处理细胞中大为缩短。结论 分离的豚鼠心肌细胞可用短时间的低氧作预处理。此低氧预处理可改变ATP敏感性钾通道 。