15-KETE对慢性缺氧大鼠肺动脉平滑肌细胞钾离子通道的作用

目的观察15-酮基二十碳四烯酸（15-ketoeicosatetraenoic acid,15-KETE）对缺氧大鼠肺动脉平滑肌细胞（pulmonary arterial smooth cells,PASMCs）膜电压门控钾离子通道的活性的影响。方法将12只雄性SD大鼠随机分成对照组和缺氧组,每组6只。采用急性酶分离法（胶原酶Ⅰ型和弹性酶）获得SD大鼠单个PASMCs,应用全细胞膜片钳记录方法,研究15-KETE对两组大鼠膜电位（Em）、膜电容（Cm）、电压门控钾电流（IKv）的影响。结果 （1）慢性缺氧使大鼠PASMCs的Em显著去极化（P〈0.05,n=6）,明显地抑制了大鼠PASMCs的IKv（P〈0.01,n=6）,对大鼠PASMCs的Cm无影响;（2）较高浓度的15-KETE（1×10^-7 mol/L、1×10^-6 mol/L）可使慢性缺氧大鼠PASMCs去极化;（3）15-KETE（1×10^-8 mol/L～1×10^-6 mol/L）可浓度依赖性地抑制慢性缺氧大鼠PASMCs的IKv;（4）较高浓度15-KETE（1×10^-7 mol/L、1×10^-6 mol/L）对缺氧PASMCs IKV的平均阻抑率显著高于常氧PASMCs。结论缺氧未改变15-KETE引大鼠PASMCs去极化及浓度依赖抑止IKv的特性,且缺氧可能改变了PASMCs对15-KETE的敏感性。

Effect of 15-KETE on Voltage-gated K＋ Current in the Intrapulmonary Arterial Smooth Muscle Cells of Chronic Hypoxic Rats

Objective To observe the effect of 15-KETE on voltage-gated K＋（Kv） current in the intrapulmonary arterial smooth muscle cells（PASMCs） of chronic hypoxic rats.Methods Twelve male SD rats matched with age and body weight were randomly divided into control and hypoxic groups.Single PASMCs were obtained with acute enzyme（collagenⅠplus elastase） dispersing method.Using whole cell path-clamp technique in freshly isolated rat PASMCs from normoxic and hypoxic rats,the effect of 15-KETE on Kv current was recorded.Results（1） The resting membrane potential（Em） in PASMCs from chronic hypoxic rats was significantly depolarized to compared with that from normoxic control rats（P 〈0.05,n = 6）.The chronic hypoxia significantly inhibited the IKv of PASMCs from rats（P〈 0.01,n =6）,but did not alter the membrane capacitance（Cm） of PASMCs from rats.（2） The higher concentration of 15-KETE（1 × 10-7 mol/L,1 × 10-6 mol/L） depolarized PASMCs from chronic hypoxic rats.（3） 15-KETE（1 × 10-8 mol/L ～ 1 ×10-6 mol/L） caused concentration-dependent inhibition of IKv in PASMCs from chronic hypoxic rats.（4） The percent inhibition that the higher concentration of 15-KETE（1 × 10-7 mol/L,1 × 10-6 mol/L） caused from chronic hypoxic rats was greater than that from normoxic control rats.Conclusions Hypoxia did not change the effect of 15-KETE on the passive electrical properties of PASMCs.In both normoxic and hypoxic PASMCs,exogenous 15-KETE could cause concentration-dependent inhibition Kv current,and the inhibition of Kv current from hypoxic rats were greater than that from normoxic rats in higher concentration（1 × 10-7 mol/L ～ 1 × 10-6 mol/L）.Hypoxia might alter the sensitivity of PASMCs to 15-KETE.