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目的和方法：用生长激素（ＧＨ）刺激培养的新生大鼠心肌细胞，用含ＭＢＰ凝胶分离法测定细胞外信号调节酶（ＥＲＫｓ）活性，用ＷｈａｔｍａｎＰａｐｅｒＦｉｌｔｅｒ法测定Ｒａｆ－１活性，观察ＧＨ是否激活心肌细胞Ｒａｆ－１－ＥＲＫ级联反应。观察负显突变Ｒａｓ质粒（Ｄ．Ｎ．Ｒａｓ）与ＨＡ－ＥＲＫ２质粒复合转染或有关抑制剂对ＧＨ诱导ＥＲＫ激活的影响。结果：ＧＨ以时间和浓度依赖性方式激活心肌细胞ＥＲＫ１和ＥＲＫ２。ＥＲＫ上游调节酶Ｒａｆ－１活性也升高。过度表达Ｄ．Ｎ．Ｒａｓ明显抑制ＧＨ诱导的心肌细胞ＨＡ－ＥＲＫ２激活。Ｒａｓ特导性抑制剂ｍａｎｕｍｙｃｉｎ也显著阻断ＧＨ诱导的心肌细胞ＥＲＫ激活。而分别用ＴＰＡ和ＣａｌｐｈｏｓｔｉｎＣ耗竭和抑制心肌细胞ＰＫＣ，均未阻断ＧＨ对ＥＲＫ的激活作用。结论：ＧＨ激活心肌细胞的Ｒａｆ－１－ＥＲＫ级联反应，这种激活依赖上游Ｒａｓ，而不受ＰＫＣ活性和含量变化的影响
PURPOSE AND METHODS: The cultured neonatal rat cardiomyocytes were stimulated with growth hormone (GH) and the activity of extracellular signal-regulated enzymes (ERKs) was determined by MBP-containing gel separation assay. Raf-1 activity was measured by WhatmanPaperFilter method to observe whether GH was activated Raf-1-ERK cascade in cardiomyocytes. To observe the effect of negative transfected Ras plasmid (D.N.Ras) and HA-ERK2 plasmid or related inhibitors on GH-induced ERK activation. RESULTS: GH activated cardiomyocytes ERK1 and ERK2 in a time and concentration-dependent manner. ERK upstream regulatory enzyme Raf-1 activity also increased. Overexpression N. Ras significantly inhibited GH-induced activation of HA-ERK2 in cardiomyocytes. Mannitinase, a specific inhibitor of Ras, also significantly blocks GH-induced ERK activation in cardiomyocytes. However, TPA and CalphostinC depletion and inhibition of myocardial cell PKC, respectively, did not block the activation of GH on ERK. CONCLUSIONS: GH activates the Raf-1-ERK cascade in cardiomyocytes and this activation is dependent on the presence of upstream Ras and is not affected by changes in PKC activity and content