ATP激活鼻咽癌细胞氯电流并减小细胞容积

采用全细胞膜片钳技术和细胞容积测量技术,在低分化鼻咽癌细胞株CNE-2Z上观察ATP 诱导的Cl- 电流的特性及其对细胞容积的影响。细胞外微摩尔水平的ATP 以剂量依赖性的方式激活一个具有弱外向整流特性,没有时间依赖性失活的电流,此电流的反转电位 (-0.05 ± 0.03) mV]接近Cl- 的平衡电位(-0.9 mV)。用葡萄糖酸置换细胞外液Cl- 后, ATP 激活的电流明显减小并且反转电位发生改变。氯通道抑制剂NPPB (200 μmol/L)可以抑制这一电流 (81.03 ± 9.3)%] 。此电流亦可被嘌呤受体(P2Y) 拮抗剂反应蓝 2 抑制 (67.39 ± 5.06)%]。50 μmol/L 的 ATP 使在等渗状态下的细胞容积缩小, 替代和耗竭细胞外、内的Cl- 后, ATP 的这一作用消失。这些结果提示细胞外微摩尔水平的 ATP 可通过兴奋 P2Y 受体激活氯通道而产生与细胞容积调节相关的Cl- 电流。

Activation of chloride current and decrease of cell volume by ATP in nasopharyngeal carcinoma cells

Whole-cell patch clamp and cell volume measurement techniques were used to investigate the ATP-activated chloride current and the ATP effect on cell volume in nasopharyngeal carcinoma cells. Extracellular application of ATP in micromolar concentrations activated a current with the properties of modest outward rectification and negligible time-dependent inactivation in a dose-dependent manner. The current reversed at a potential (-0.05+/-0.03) mV] close to the Cl- equilibrium potential (-0.9 mV). Substitution of Cl- with gluconate in the extracellular solution decreased the ATP-activated current and shifted the reversal potential positively. NPPB, one of the chloride channel blockers, inhibited the current by (81.03+/-9.36)%. The current was also depressed by the P2Y purinoceptor antagonist, reactive blue 2, by (67.39+/-5.06)%. ATP (50 micromol/L) decreased the cell volume under the isotonic condition. Depletion of extracellular and intracellular Cl- abolished the ATP effect on cell volume. The results suggest that extracellular ATP of micromolar scales can induce a chloride current associated with cell volume regulation by activation of chloride channel through binding to purinoceptor P2Y.