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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 ,使之在再次低氧时更快开放
OBJECTIVE: To establish a cell preconditioning model of isolated guinea pig cardiomyocytes by hypoxia for a short period of time and to determine whether ATP-sensitive potassium channel is involved in this hypoxic (ischemic) preconditioning. Methods Single cardiomyocytes were isolated from the ventricular of adult guinea pigs and the experimental perfusion tank allowed these cells to be exposed to hypoxic perfusate to be in hypobaric condition. During hypoxic preconditioning, cells were first equilibrated in normal solution for 10 minutes and then hypoxic perfusate for 5 minutes followed by 10 minutes of reoxygenation. These pretreated cells were given hypoxia for 20-180 minutes and reoxygenated. Whole-cell and single-channel recordings were performed using patch clamp techniques to investigate ion flux changes. Results The hypoxic preconditioning for 5 minutes provided significant protection against injury induced by hypoxia-reoxygenation. After a delay of more than 15 minutes, hypoxia induced a non-time-dependent potassium outflow that could be blocked by 5 μmol / L of glyburide. This current increased from 78 ± 15 pA to 1581 ± 153 pA (P <0 0 1, n = 18) at depolarization to 10 mV. However, the delay in generating ATP-sensitive potassium channel currents was much shorter and faster in pretreated cells. Over 4nA at 10mV. In single-channel recording, the time span from the opening of the first channel to the maximum opening was greatly reduced in the pre-treated cells. Conclusion The isolated guinea pig cardiomyocytes can be pretreated with hypoxia for a short time. This hypoxic preconditioning alters the ATP-sensitive potassium channels, allowing them to open more quickly once again under hypoxia