摘要
目的 探讨 Na+ /Ca2 +交换体电流 (INa+ /Ca2 + )在左室肌不同部位的分布特征及其与跨壁复极异质性的关系。方法 采用全细胞膜片钳技术 ,分别记录兔左心室肌内膜下、中层及外膜下细胞的动作电位 (AP)、INa+ /Ca2 + 及 IK。结果 中层细胞 AP时程明显长于外膜下细胞 (P<0 .0 1 ) ;在 +40 m V时 ,外向 INa+ /Ca2 + 密度在中层细胞明显大于外膜下及内膜下细胞 (P分别 <0 .0 1 ,0 .0 5 ) ;在 - 1 0 0 m V时 ,内向 INa+ /Ca2 + 密度在中层细胞明显大于外膜下 (P<0 .0 5 ) ;在测试电压为 +5 0 m V时 ,中层细胞的 IKs尾电流密度明显小于外膜下细胞 (P<0 .0 5 ) ,内膜下、中层及外膜下细胞的 IKr尾电流密度无明显区别 (P>0 .0 5 )。结论 INa+ /Ca2 + 与 IKs在兔左室肌的分布具有异质性 。
Objective To investigate the distribution characteristics of Na +/Ca 2+ exchanger current (I Na +/Ca 2+ ) across the left ventricular wall of rabbit and the relationship between I Na +/Ca 2+ and transmural depolarization heterogeneity. Methods By using whole cell patch clamp techniques, action potentials(AP), I Na +/Ca 2+ , and both rapid and slow components of delayed rectifier potassium current(I Kr and I Ks ) were recorded in subendocardial(Endo), midmyocardial(M), and subepicardial(Epi) cells of the left ventricular wall of rabbit. Results AP duration in M cells was longer than that in Epi cells, P <0.01. At the test potential of +40 mV, outward I Na +/Ca 2+ in M cells was larger than that in Epi and Endo cells, P <0.01, P <0.05, respectively. At the test potential of -100 mV, inward I Na +/Ca 2+ in M cells was larger than that in Epi cells, P <0.05. At the test potential of +50 mV, the tail current density of I Ks in M cells was smaller than that in Epi cells, P <0.05, and there was no significant difference among the tail current densities of I Kr in Endo, M, and Epi cells. Conclusion The distribution of I Na +/Ca 2+ and I Ks across the left ventricular wall of rabbit is unequal, which contributes to the transmural depolarization heterogeneity.
出处
《四川大学学报(医学版)》
CAS
CSCD
北大核心
2004年第4期496-499,共4页
Journal of Sichuan University(Medical Sciences)