摘要
目的 :研究新西兰纯种大白兔左心室游离壁 3层心肌细胞的形态特征及其快钠通道电流 (INa)特性的异质性。方法 :采用胶原酶酶解法分离兔左室游离壁 3层心肌细胞 ,以全细胞膜片钳技术记录快钠电流的动力学特性。结果 :1兔左室游离壁 3层心肌细胞的形态特征相似 ;2 3层细胞的 INa I-V曲线均呈电压依赖性 ,形态轨迹一致。 3层细胞中 M细胞的 I-V曲线最低 ,心内膜和心外膜层的依次向上。INa峰值电流密度在 -2 0 m V时 M,Epi和 Endo细胞分别为 -3 1± 8、-16± 7和 -12± 2 p A/p F(n=12 cells) ,M细胞的 INa电流密度明显大于 Epi、Endo。 M细胞的INa稳态失活曲线在最左边 ,向右依次为 Epi和 Endo细胞 ,M的 INa失活最快。 3层细胞的 INa失活后恢复曲线无显著性差异。结论 :兔左室游离壁 3层心肌细胞的形态特征相似 ,INa的分布及动力学特性存在异质性 。
AIM: To study the features of the sodium current (I Na ) of epicardial, midmyocardial and endo cardia l myocytes from rabbit left ventricles. METHODS: Single myocyte was di ssociated e nzymatically and I Na was recorded using whole-cell patch clamp techniques . RESULTS : The I Na current density-voltage relationship was voltage-dependent. Among the three groups, midmyocardial cells had the largest, and epicardial cells the smallest I-V curves. The peak I Na densities of the M, Endo and Epi at -20 mV were -31±8,-16±7 and -12±2 pA/pF ( n =12 cells). The peak I Na den sity w as greater in the M cells than in the Epi and Endo cells( P = 0.000 and 0.00 1, respec tively). The I Na steady-i nactivation curves of the Epi, M and Endo cells were voltage-dependent and shap ed as ' reverse S' type. Among the three groups, M cells inactivated faster than the ot h er two groups. There were no significant differences in the I Na recovery c urves from inactivation among the three types of myocytes. CONCLUSION: The m orphological characteristics of Epi, M and Endo cells are similar. The transmur al heterogeneity of I Na may be the ionic bases of the differences in morphology of the action potentials among three types of myocytes,and may be responsible for some reentant arrhy thmias.
出处
《心脏杂志》
CAS
2003年第6期481-484,共4页
Chinese Heart Journal
