非洲爪蟾卵母细胞内源性ATP激活电流I_D2成分的分析

非洲爪蟾卵母细胞内源性ATP激活电流I D2 成分的分析 Analysis of the I D2 Component of Endogenous ATP-Induced Inward Currents in Follicular Oocytes of Xenopus Laevis 万曙霞 1 2 3 4 first-author 李之望 1 2 3 4 魏劲波 1 2 3 4 彭碧文 1 2 3 4 张奇仕 1 2 3 4 武汉大学医学院生理学教研室 武汉大学医学院生理学教研室 华中科技大学同济医学院神经生物学系 华中科技大学同济医学院神经生物学系 ,湖北,武汉,430030 ,湖北,武汉,430030 在带有滤泡膜的非洲爪蟾卵母细胞标本上 ,应用双电极电压钳及胞内透析方法进行记录 ,外加 ATP所激活的内源性膜电流包括 3个成分依次为 :快内向电流 （early fast depolarizing current,ID1 ） ,慢内向电流 （lateslow depolarizing current,ID2 ）和慢外向电流 （slow hygerpolarizing current,IH） .本文主要分析 ID2 成分的特性及其产生的机制 .结果如下 :（1）胞内透析 5 0 0 μmol/L GDP- β- S,5 0 min后被完全阻断 ;（2 ）外液中 [Cl- ]从 10 0 mm ol/L 下降到 5 mm ol/L 时 ,在 ATP（10 0 μm ol/L）作用下 ,ID2 幅值随 [Cl- ]的下降明显增大 ;（3）外液中无 Na+时 ID2 幅值增高 （P<0 .0 5 ） .结果表明 :ID2 是由 P2 Y受体所介导 ,通过 G蛋白耦联及胞内信号转导而引起胞内 Ca2 +依赖性Cl- 外流所致 . The experiments were performed on follicular Xenopus laevis oocytes using two-electrode voltage-clamp technique and intracellular dialysis method. ATP applied externally could induce endogenous membrane currents, which consisted of three components, i.e. I D1 , early fast deplarizing inward current; I D2 , late slow lasting depolarizing inward current and I H, slow hyperpolarizing outward current. The present study aimed to analysis the characteristics of I D2 components of ATP-induced currents （I ATP ） and their underlying mechanisms. The results observed are as follows: （1） The amplitude of I D2 was attenuated by around 50% 10 min after intracellular dialysis of 500 μmol/L GDP-β-S and almost completely abolished 30 min after the dialysis; （2） With the decrease in Cl - content in Ringer’s Solution from 100 to 5 mol/L via substituting SO 2- 4 for Cl - in Ringer’s solution, the amplitude of I D2 component of ATP （100 μmol/L）-induced current increased markedly, and the reversal potential shifted from （-20±2.1） mV to （+1.35±0.75） mV. （3） After displacing NaCl in Ringer’s solution with equimolar choline chloride, the amplitudes of I D2 at the 4 different concentrations of ATP from 1 to 1000 μmol/L were higher than the controls markedly. It comes to the conclusion that in Xenopus oocytes I D2 , a Ca 2+ dependent Cl - current, is mediated by P 2Y purinoceptor via G protein coupling and corresponding intracellular signal transduction process. 带滤泡膜的卵母细胞 ATP受体 ATP激活电流ID2成分 电压钳记录 胞内透析 follicular Xenopus oocyte receptor for ATP I D2 component of ATP-induced current voltage-clamp recording intracellular dialysis Q67 国家自然科学基金资助课题 （ 39870 2 5 9） 2001-06-01 2021-04-01 6