细胞外信号调节激酶对心肌细胞钠氢交换体调控的作用

Effects of extracellular regulated protein kinase on Na^+-H^+exchanger in neonatal rat cardiomyocytes

目的:探讨细胞外信号调节激酶(ERK)对心肌细胞钠氢交换体(NHE)的调控作用。方法:用氯化铵诱导乳鼠心肌细胞内酸化,用荧光指示剂(BCECF/AM)法测定细胞内pH值,钠氢交换体的活性用酸化后每分钟pH值的变化率(dpH_i/dt)表示,观察使用ERK特异性抑制剂UO126后对NHE活性的影响;用Western blottmg检测心肌细胞ERK蛋白的磷酸化水平。结果:用ERK的选择性抑制剂UO126(3μmoL/L)预孵育5 min,与模型组比较,UO126组可以使钠氢交换的活性下降49.46%(P<0.05);与模型组比较,ERK的磷酸化水平降低66.5%(P<0.05)。结论:细胞内酸化激活NHE和ERK的过程中,NHE的激活受到ERK的调控。

Objective ：To investigate the action on Na ^＋ - H^＋ exchanger （NHE） by extracellular regulated protein kinase （ERK）. Methods： Intracellular acidosis was induced with ammonium chloride in cardiomyocytes of neonatal rats. The cardiomyocytes were then measured for intracellular pH using a fluorescence indicator （BCECF/AM）. The action of specific ERK inhibition U0126 on post-acidification NHE activity,as calculated by the rate of pHi recovery （ dpHi/dt ） , was studied. Expression of extracellular regulated protein kinase was determined by western blotting. Results： Compared with the untreated model group, 5-min incubation with the selective ERK inhibitor U0126 （3 μmol/L） was shown to reduce the activity of Na^＋/H^＋ exchanger by 35.3% （P 〈 0.05 ）, and the level of phosphor-ERK protein by 66.5 % （P 〈 0.05 ）. Conclusion： During intracellnlar acidosis-induced activation of NHE and ERK, the activation of Na^＋/H ^＋ exchanger is regulated by extracellular regulated protein kinase in neonatal rat cardiomyocytes.