人脐静脉血管内皮细胞容量激活和钙激活氯离子通道(英文)

目的:研究人脐静脉血管内皮细胞的氯离子通道及其不同的调节机制。方法:全细胞膜片箝技术。结果:13.5％和27％的低渗液体灌流细胞激活一外向电流(I_(Cl·vol))。该电流有弱的外向整流特性,无明显时间和电压依赖性;电流大小为(58±5)pA/pF;分别为(20±3),(58±4)增加细胞内钙或胞外应用ATP能激活I_(Cl,Ca)。该电流幅值较小(23±5)pA/pF;外向整流特性明显,在正电压下缓慢激活。两种电流均被DIDS及维拉帕米抑制。在同一个细胞上,在激活I_(Cl,Ca)的基础上灌流低渗液体可进一步激活I_(Cl,vol)。结论:HUVEC表达有两种氯通道,改变细胞容积可激活I_(Cl,vol),而增加细胞内钙则诱导出I_(Cl,Ca)。

Volume- and calcium-activated chloride channels in human umbilical vein endothelial cells

AIM: To characterize the properties of chloride currents and its modulation in human umbilical vein endothelial cells (HUVEC). METHODS: Using whole-cell patch-clamp recording techniques. RESULTS: Exposure of HUVEC to 13.5% and 27% hypotonic solution (HTS) induced a current ICl, vol. This current was correlated with the changes in cell volume and showed a modest outward rectification. It was slowly inactivated at positive potential (> 50 mV), and it was time- and voltage-independent in kinetics. The current densities (pA/pF) were 20 +/- 3 (13.5% HTS) and 58 +/- 4 (27% HTS, n = 7), respectively at +100 mV test potential. Applying GTP gamma s (300 mumol.L-1) elicited a current similar to ICl, vol, while cAMP (0.5 mmol.L-1) had no effect on the current. Increase in Ca2+]i, either by directly loading cells with high concentration of Ca2+ (CaCl2), or by perfusing vasoactive agonist ATP (10 mumol.L-1), activated ICl, Ca. The current density was only (23 +/- 5) pA/pF (n = 8 cells). Such current was slowly activated at positive potential, inactivated quickly at negative potential, and showed strong outward rectification. Both currents were inhibited by DIDS and verapamil. Challenging a cell with elevated Ca2+]i and HTS activated ICl, vol on the top of ICl, Ca in the same cell, suggested co-existence of these two currents and that they were modulated by different ways. cAMP-regulated chloride channel and ClC (chloride channel family) channel were absent. CONCLUSION: HUVEC express two kinds of chloride channels, ICl, vol activated by change in cell volume and ICl, Ca by elevation of Ca2+]i, respectively.