中文摘要：

目的探讨急性缺血对窦房结起搏细胞起搏电流（If）影响的机制。方法将兔窦房结起搏细胞分为三组，均先灌流正常台式液，电流稳定后实验Ⅰ、Ⅱ组分别灌流含5．4、10mmol／L KCl的缺血样台式液，实验Ⅲ组灌流含10mmol／LKCl台式液，灌流5～8min，再用正常台式液冲洗；采用穿孔膜片钳技术记录If。结果实验Ⅰ组If电流密度在舒张期膜电位（-60～-70mV）无显著变化；实验Ⅱ组Ⅰ，电流密度在测试电位（-60～-110mV）均显著增强（P〈0．05）；而实验Ⅲ组If电流密度亦显著增强（P〈0．05）。结论急性缺血伴有细胞外高钾可显著增强兔窦房结起搏细胞If电流密度，其机制可能与细胞外高钾有关。

英文摘要：

Objective To investigate the effect of acute iachemia on hyperpolarization-activated nonselective inward current （If） in isolated sino-atrial node （SAN） pacemaker ceils （PCs） and to explore its mechanism. Methods The enzymatically isolated SAN PCs from rabbit were divided into three groups, the PCs in group Ⅰ and group Ⅱ were perfused with iachemic llke solution contained 5.4 or 10 mmol/L KCl respectively, the PCs in group Ⅱ were peffused with Tyrode solution contained 10 mmol/L KCl. The PCs were first exposed to normal Tyrode solution （control） and then to experimental solution for 5 - 8 min after If was stable, followed by washout with normal Tyrode solution again. A perforated whole-ceil patch-damp techniques were used to record If. Results If at diastolic potentials （ -60 to -70 mV） was not altered significantly in group Ⅰ. If increased significantly at all test potentials （ -60 to - 110 mY） in group Ⅱ and group Ⅲ. Conclusions The acute iachemia can enhance the If of isolated sino-artial SAN Pcs from rabbit, which may due to the higher extraceilular K.