小鼠心肌细胞的容积敏感性氯通道

The volume-sensitive chloride channel in mouse cardiac myocytes

目的 :记录并研究急性分离小鼠心肌细胞容积敏感性氯通道电流的电生理学特征。方法 :采用全细胞膜片钳记录方法 ,记录急性分离的小鼠心肌细胞暴露于低渗溶液时 ,细胞体积增大后 ,出现的容积敏感性氯通道电流(volume_sensitivechloridechannelcurrent,ICl,Vol)。结果 :小鼠心肌细胞容积敏感性氯通道电流以外向电流占优势 ,在去极化正电压时有时间依赖性失活 ,电流_电压曲线显示其反转电位 [(_34.5± 0 .8)mV]接近氯离子平衡电位的理论值 (ECl=_38.6mV) ,且反转电位随细胞外氯离子浓度的改变而改变 ,Nerst方程常数为 4 3.9。电流的激活依赖于细胞内ATP。该通道的阴离子选择性为I_>Br_>Cl_,相对通透比为 2 .32∶1 .2 8∶1。结论 :小鼠心肌细胞具有明显的容积敏感性氯通道电流 。

Objective:To characterize the volume_sensitive chloride channel (I Cl,Vol ) in isolated cardiac myocytes of mouse. Methods:The cardiac myocytes were isolated from mouse heart and the whole_cell patch clamp was employed.Results:Affer exposure of the cardiac myocytes to a hypotonic solution,a volume_sensitive chloride current was activated. Time_dependent inactivation was observed at large positive potentials. The current_voltage relationship showed that the reversal potential of the hypotonic_activated current (_34.5±0.8?mV) was close to the calculated equilibrium potential for Cl _(E Cl =_38.6?mV). When the extracellular Cl _ concentration changed, the reversal potential (E rev ) of the current also shifted. The E rev shifted per 10_fold of o was 43.9?mV . The activation of the current depended on intracellular ATP. The anion permeability order of volume_sensitive Cl _ current was I _>Br _ >Cl _. A relative permeability of I _ and Br _ to Cl _ was 2.32∶1.28∶1.Conclusions:In mouse cardiac myocytes , the volume_sensitive Cl _ current that is dependent on intracellular ATP has an outward rectification and time_dependent inactivation at positive potential.[