Ca~(2+)经钙激活非选择性阳离子通道进入ECV304内皮细胞

目的　研究钙离子进入ECV30 4内皮细胞株的途径和血管紧张素Ⅱ (AⅡ )对钙内流的影响。方法　用膜片钳的细胞贴附式和全细胞方式记录ECV30 4内皮细胞的通道活动。结果　 (1 )在记录单通道电流时电极液含 1 2 0mmol·L- 1 CaCl2 ,细胞浴液不含K+ 、Na+ 时 ,Ca2 + 经非选择性阳离子通道 (CAN)内流的电导为γ0 =(1 2 90± 2 1 1 ) pS(n =4)。1× 1 0 - 7mol·L- 1 AⅡ可显著增强通道电流幅度和延长通道开放时 ,其电导增大为γ1 =(2 2 1 8± 2 2 9)pS(n =4)。全细胞记录得到的结果与单通道的一致。 (2 )用全细胞方式记录到ECV30 4内皮细胞的电压依赖性钙通道电流 ,记录到该峰值电流为 (2 9 32± 3 56)pA(n =4) ,2 0 μmol·L- 1 nifedepine能抑制这个峰值电流 ,被抑制后的电流峰值为 (6 0 0± 3 94)pA(n =4)。 2 μmol·L- 1 BayK8644能显著激活通道活动。结论　Ca2 + 经CAN进入ECV30 4细胞 ,AⅡ可显著增强CAN的钙流

Entery of calcium into ECV304 endothelial cell via Ca2+-activated non-selective cation channel

AIM To investigate the pathways of Ca 2+ entry into ECV304 endothelial cell and the effect of angiotensin Ⅱ(AⅡ) on calcium activated non setective cation channel(CAN). METHODS The cell attachment and whole cell configurations of patch clamp technique were used to record channel activity. RESULTS (1) The single channel conductance is γ o=(12 90±2 11) pS( n =4) for Ca 2+ passing through CAN of ECV304 cell in condition of pipette solution without K + and Na + but composed 120 mmol·L -1 CaCl 2. The channel current amplitude and open time can be enhanced by 1×10 -7 mol·L -1 AⅡ. The enhanced conductance in CAN is γ 1=(22 18±2 29) pS( n =4). The results of whole cell recording are identified with single channel recording. (2) The whole cell configuration was carried out for recording voltage dependent Ca 2+ channel in ECV304 cell. The peak current amplitude was (29 32±3 56) pA( n =4). This current was inhibited to (6 00±3 94) pA( n =4) by nifedipine and activated by BayK8644. CONCLUSIONS (1)Ca 2+ enters ECV304 cell via Ca 2+ activated non selective cation channel and voltage dependent L type calcium channel. (2) AⅡ can significantly enhance the calcium entry via CAN in ECV304 cell.