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目的研究汞对P2X4嘌呤受体介导的ATP-激活电流(ATP-activated currents,IATP)的影响及其特征。方法将编码大鼠P2X4受体的cDNA在体外转录成cRNA,通过显微注射技术将该cRNA注入非洲爪蟾卵母细胞中进行表达。应用全细胞双电极电压钳技术研究汞对P2X4受体介导的IATP的影响。结果大鼠P2X4受体能有效地表达于非洲爪蟾卵母细胞;汞对P2X4受体介导的IATP具有抑制作用;汞使ATP的量-效曲线右下移,最大效应电流比单独加入ATP时减小,汞的IC50是(8.9±5.3)μmol/L;随着汞孵育时间增加,对IATP的抑制效应也相应增加,并在5 min之后出现最大抑制效应;钳制电位为-120,-100,-60,-40,-20,20(mV)的情况下,汞对IATP的抑制作用差异无统计学意义。结论汞抑制P2X4受体介导的IATP具有可逆性、浓度依赖性和时间依赖性,无电压依赖性。
Objective To investigate the effect of mercury on P2X4-mediated purging of ATP-activated currents (IATP) and its characteristics. Methods cDNA encoding rat P2X4 receptor was transcribed into cRNA in vitro and injected into Xenopus laevis oocytes by microinjection to express it. Whole cell bipolar voltage clamp technique was used to study the effect of mercury on P2X4 receptor mediated IATP. Results The P2X4 receptor of rat was effectively expressed in Xenopus laevis oocytes. Mercury had an inhibitory effect on P2X4 receptor-mediated IATP. Mercury decreased the ATP-ATP curve to the right, and the maximal effect current was lower than that of ATP alone The IC50 of mercury was (8.9 ± 5.3) μmol / L, the inhibitory effect on IATP increased with the increase of mercury incubation time, and the maximum inhibitory effect appeared after 5 min. The clamp potential was -120, 100, -60, -40, -20, 20 (mV), the inhibitory effect of mercury on IATP was not statistically significant. Conclusions Mercury inhibits P2X4 receptor-mediated IATP in a reversible, concentration-dependent and time-dependent manner, with no voltage dependence.