ATP诱导的血管内皮细胞氯电流及其与Ca~(2+)运动的关系

采用全细胞膜片钳技术和fura 2荧光测定胞浆 Ca2 +]i 变化技术 ,在培养的牛主动脉内皮细胞上观察ATP诱导的Cl- 电流的特性及其与Ca2 +内流的关系。记录到ATP激活一外向电流 ,其反转电位为 - (2 9± 8)mV ,与Cl- 的平衡电位接近 ,降低细胞外Cl- 浓度使反转电位变化 ,证明是Cl- 电流 .ATP激活的Cl- 电流具有较强的外向整流特性 ,具有Ca2 +依赖性 ,可被Cl- 通道阻滞剂呋塞米和格列本脲分别最大抑制 (88± 8) %和 (93± 4 ) % (+ 10 0mV) .ATP又可诱导内皮细胞外Ca2 +内流 ,呋塞米和格列本脲对Ca2 +内流分别最大抑制 (36± 14) %和 (44± 12 ) % ,并且二者敏感的Ca2 +内流特性不同 .结果说明Cl- 通道开放在调节内皮细胞Ca2 +内流中起重要作用

ATP-induced chlorine current in vascular endothelial cells and its relationship with Ca2+ movement

The combination of whole-cell patch clamp and fura-2 fluorescence techniques had been used to investigate the ATP-activated Cl- current and Ca2+ entry in bovine aortic endothelial cells (BAEC). Application of ATP activated an outward current. The I-V curve showed pronounced outward rectification and the current reversed at －(29±3)mV, which was close to the equilibrium potential for Cl- (－36 mV). Reducing the ［Cl-］o caused a shift in the reversal potential towards more positive potentials. It indicated that the ATP-activated current was mainly carried by Cl-. ATP-activated Cl- current was ［Ca2+］i dependent, it was maximally inhibited by Cl- channel blockers furosemide and glibenclamide with (88±8)% and (93±4)% at +100 mV. Application of ATP activated Ca2+ influx from the extracellular space. ATP-induced Ca2+ entry was inhibited by furosemide and glibenclamide with (36±14)% and (44±12)%, respectively. The Ca2+ influx sensitive to furosemide is not the same as that to glibenclamide. These observations suggest that opening of Cl- channel plays an important role in the regulation of Ca2+ entry in BAEC.