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

作　　者：万曙霞[1] 李之望[2] 魏劲波[1] 彭碧文[1] 张奇仕[1] 

机构地区：[1]武汉大学医学院生理学教研室,湖北武汉430071 [2]华中科技大学同济医学院神经生物学系,湖北武汉430030

出　　处：《武汉大学学报（理学版）》2001年第6期752-752,共1页Journal of Wuhan University:Natural Science Edition

基　　金：国家自然科学基金资助课题 ( 39870 2 5 9)

摘　　要：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.

关 键 词：卵母细胞 ATP受体 非洲爪蟾 电压钳记录 胞内透析 内源性膜电流 电流成分 

分 类 号：Q959.53[生物学—动物学] Q64