镧对MC3T3细胞钙激活钾电流及其动力学的影响  

Effects of lanthanum on calcium-activated K^+ currents and its kinetics in MC3T3 cells

作　　者：张丽平[1,2,3] 杨频[2,3] 

机构地区：[1]太原科技大学环境科学研究所,太原030024 [2]化学生物学与分子工程教育部重点实验室 [3]山西大学分子科学研究所,太原030006

出　　处：《中国科学：化学》2010年第8期1011-1017,共7页SCIENTIA SINICA Chimica

基　　金：国家自然科学基金重大项目(20637010);山西省自然科学青年基金项目(2007021010)资助

摘　　要：利用全细胞膜片钳技术,研究了稀土镧离子对非兴奋性小鼠成骨细胞(MC3T3)钙激活外向钾电流及其激活和失活动力学的影响.结果表明:MC3T3细胞钙激活外向钾电流随着电极内液中游离Ca2+浓度的增加而增加,且具有电压和胞内游离Ca2+依赖性特征.细胞外液中的稀土镧可浓度依赖性地抑制MC3T3细胞钙激活外向钾电流,其半数抑制浓度(EC50)为8.23±1.45μmol/L.50μmol/L氯化镧可使钾电流的激活曲线向正电位方向移动,而使其失活曲线向负电位方向移动,但对激活曲线和失活曲线的斜率因子k值影响都不大.研究表明:抑制钾通道电流,可使细胞膜去极化,细胞的兴奋性增加,从而增加胞外Ca2+向胞内流动,引起胞内Ca2+浓度的增加,由此而诱发一系列的生理和分子生物学事件.这一过程可能是稀土镧影响MC3T3成骨细胞生长和功能的分子作用机制之一.Using the whole cell patch-clamp technique,we studied the effects of La^3＋ on calcium-activated K^＋ currents and its kinetics of activation and inactivation in non-excitable MC3T3 cell. Our results showed that the calcium-activated outward K^＋ currents were promoted with increasing concentration of Ca^2＋ in pipette solution and were in a voltage-and Ca^2＋-dependent manner. La^3＋ in bath solution inhibited the currents in a concentration-dependent manner and the inhibition EC50 was 8.23±1.45 μmol/L. At the concentration of 50 μmol/L,La^3＋ significantly changed the Vh of activation curve and shifted the activation curve to more positive potentials,but shifted the inactivation curve to more negative potentials. It had no effect on the slope factor k of the activation and inactivation curves. Potassium currents inhibition could induce a series of physiological and molecular biological functions,presumably because of its ability to depolarize the plasma membrane and enhance cell excitability,resulting in increasing Ca^2＋ influx and cytoplast Ca^2＋ concentration. This process may be one of the molecular mechanisms by which La^3＋ affects the cell growth and function of MC3T3 cells.

关 键 词：MC3T3细胞 钾通道 镧离子 膜片钳技术 

分 类 号：R341[医药卫生—基础医学]