表达在爪蟾卵母细胞上的大鼠P2X_4受体介导的ATP-激活电流特征

本研究应用显微注射和双电极电压钳技术对P2X4受体介导的三磷酸腺苷(ATP)-激活电流(IATP)的特征进行了研究。结果显示:(1)大鼠P2X4受体可高效表达于非洲爪蟾卵母细胞;(2)外加1μmol/L、10μmol/L和100μmol/LATP,IATP激活相的时间常数τon分别是3.58s±0.20s、2.30s±0.21s和1.3s±0.14s。IATP快失敏相的时间常数τdes分别是11.74s±0.11s、7.52s±0.24s和4.11s±0.18s。IATP慢失敏相的时间常数τoff分别为14.25s±2.30s、25.42s±4.45s和35.71s±5.92s;(3)ATP作用的量-效关系:EC50为(16.03±1.81)μmol/L,Hill系数为1.02±0.09;(4)100μmol/L的PPADS和suramin不改变IATP的幅值;(5)IATP呈电压依赖性和内向整流特性;(6)加药时间分别为20s、30s、45s和60s的情况下,IATP幅值并无显著性差异。以上结果说明了P2X4受体介导的ATP-激活电流的特征,为进一步研究P2X4受体的功能和调控机制奠定了基础。

Characteristics of ATP-activated current mediated by rat P2X4 receptor expressed in the Xenopus oocytes

In the present study,we used microinjection and two-electrode whole-cell voltage clamp to explore the characteristics of ATP-activated current(IATP)mediated by rat P2X4 receptor expressed in Xenopus oocytes.Our results showed that:(1)The rat P2X4 receptor could be efficiently expressed in Xenopus oocytes.(2)The activation phase time constant(τon)of IATP were 3.58 s±0.20 s,2.30 s±0.21 s and 1.3 s±0.14 s,respectively;fast desensitizing phase time constant(τdes)of IATP were 11.74 s±0.11 s,7.52 s±0.24 s and 4.11 s±0.18 s,respectively,while slow desensitizing phase time constant(τoff)of IATP were 14.25 s±2.30 s,25.42 s±4.45 s and 35.71 s±5.92 s,respectively;when 1 μmol/L,10 μmol/L,and 100 μmol/L ATP are applied correspondingly.(3)The concentration-response relationship in ATP was measured as:(16.03±1.81)μmol/L of EC50 to 1.02±0.09 of Hill coefficient.(4)PPADS and suramin at a concentration of 100 μmol/L had no effect on IATP mediated by rat P2X4 receptor.(5)IATP exhibits characteristics of both voltage-dependency and inward-rectification,and(6)IATP did not have a significant variation when applying ATP times are 20 s,30 s,45 s,and 60 s.The results in this study advance our understanding in the characteristics of IATP,and prepare for further investigation in the functions of P2X4 receptor and its inner modulating mechanism.