目的：研究异丙肾上腺素（ISO）对乳鼠窦房结细胞自动节律和钠钙交换电流（INCX ）的作用。方法选12只新生24 h内Wistar大鼠乳鼠分离培养窦房结细胞，运用全细胞膜片钳技术记录动作电位（AP）和 INCX电流。结果于细胞外加入 ISO 1．0μmol／L 后，AP 的发生频率明显增加，从（147．9±9．9）min－1增加至（278±11．2） min－1。ISO可使＋80 mV起始时外向 INCX密度从（0．52 ± 0．03）pA／pF增加至（0．72 ± 0．04）pA／pF （n＝10，P＜0．05），平均增加约36．7％；而－120 mV时内向电流从（－3．26 ± 0．02）pA／pF增加至（－7．81 ± 0．06） pA／pF（n＝10，P＜0．01）。此效应呈现电压依赖性和浓度依赖性特征。结论乳鼠窦房结细胞 INCX参与窦房结自动去极化，ISO可使其作用增加。%Objective To investigate effect of isoproterenol on spontaneous rhythm and INCX in new born rat’s sino‐atrial node cell . Methods The sino‐atrial node cells of newborn Wistar rats were enzymatically disassociated by the method of enzyme digestion with differential attachment .Whole‐cell patch clamp technique was used to record INCX . Results The spontaneous rhythm in sino‐atrial node cells was significantly enhanced by ISO 1 .0 μmmo/L . INCX was larger after exposure to ISO in voltage‐ and concentration‐dependent fashion . At +80mV of test potential ,outward current densities of INCX were in‐creased from (0 .52 ± 0 .03) pA/pF to (0 .72 ± 0 .04) pA/pF (n=10 ,P<0 .05) ,meanwhile ,inward current densities of INCX at -120 mV were increased from (-3 .26 ± 0 .02) pA/pF to (-7 .81 ± 0 .06) pA/pF (n=10 ,P<0 .01) . Conclusion INCX participates in the sino‐atrial node automatically depolarization in new born rat’s sino‐atrial node cells ,w hich is regulated by ISO .
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