犬左右心室肌细胞L型钙电流不均一性的研究

目的测定犬左、右心室3层心肌细胞上参与离子流平衡的内向电流L型钙电流(ICa.L)的特性。方法经酶解分离获得犬左、右心室外膜下细胞、M细胞和内膜下细胞,应用全细胞膜片钳技术,记录并比较不同部位心肌细胞的ICa.L,分析电流-电压曲线。结果ICa.L的峰值电流密度(pA/pF)在右心室外膜下细胞、M细胞和内膜下细胞分别为:-4.896±1.907(n=31),-3.406±0.904(n=37)和-2.788±0.756(n=33),心外膜下心肌细胞与M细胞比较,差异有统计学意义(P<0.05);在左心室分别为:-3.824±1.201(n=18),-4.854±1.485(n=20)和-2.988±1.082(n=17),3者之间两两比较,差异有统计学意义(P<0.05)。ICa.L的峰值电流密度在右心室心外膜下心肌细胞大于左心室(P<0.05),而右心室M细胞小于左心室(P<0.01),心内膜下心肌细胞左、右心室之间差异无统计学意义(P>0.05)。结论ICa.L在犬左、右心室肌的不同细胞(外膜下心肌细胞、M细胞、内膜下心肌细胞)存在不均一性,导致右心室跨室壁的电不均一性较左心室明显。

Study of Electrical Heterogeneity of L-type Calcium Current witn Ventricular Myocytes in the Canine

Objective To determine the characteristics of L-type calcium current(_{ICa L}) in epicardial(Epi), midmyocardial (M), and endocardial(Endo) canine ventricular myocytes. Methods Using whole-cell patch clamp techniques to compare the electrophysiological characteristics of _{ICa L} of myocytes enzymatically dissociated from right and left canine ventricular epi, mid and endomyocardium. Results The peak density of _{ICa L}(pA/pF) was –4.896±1.907(n=31), -3.406±0.904(n=37), -2.788±0.756(n=33), respectively in right ventricular(RV) epicardial, midmyocardial, and endocardial myocytes(P<0.01). The peak density of _{ICa L}(pA/pF) was -3.824±1.201(n=18), -4.854±1.485(n=20), -2.988±1.082(n=17), respectively in left ventricular(LV) (P<0.01). In epicardial myocytes, the average peak _{ICa L} densities was significantly smaller in RV than in LV(P<0.05). In midmyocardial myocytes, the average peak _{ICa L} densities was significantly larger in RV than in LV(P<0.01). In endocardial myocytes, the average peak _{ICa L} densities wasn't significantly different(P> 0.05). Conclusion L-type calcium current on different ventricular myocytes of canine present with different characteristics.