The Change of Hypertrophic Signaling during the Development of Cardiac Hypertrophy and Its Regulation by Reactive Oxygen Species

目的：分析活性氧（ROS）对成年大鼠心肌细胞肥厚信号的调控作用。背景：活性氧调节各种细胞类型的有丝分裂信号转导。在新生大鼠心肌细胞中，抗氧化剂已被证明可以抑制心肌肥厚，ROS被认为可以调节肥厚信号。然而，由于新生儿心肌细胞与成人心肌细胞的性质不同，该结论可能不能反映成熟心脏的情况。方法：用内皮素-1 （ET-1）或苯肾上腺素（PE）刺激培养的成年大鼠心肌细胞，检测细胞内ROS水平、丝裂原活化蛋白激酶（MAPKs、ERK、p38、JNK）活性和3h -苯丙氨酸掺入。我们还研究了肌细胞抗氧化预处理对MAPK活性和心肌肥厚的影响，以分析氧化还原状态对MAPK介导的肥厚信号的调节作用。结果：ET-1或pe刺激的肌细胞中ROS水平在刺激后5min显著升高。ROS的来源似乎是NADH/NADPH氧化酶，因为用NADH/NADPH氧化酶抑制剂二苯乙烯酮预处理肌细胞可以抑制ROS的增加。细胞外信号调节激酶（ERK）活性通过ET-1或PE的刺激而增加。相比之下，p38和c- jun - n末端蛋白激酶（JNK）活性在这些刺激后没有变化。肌细胞的抗氧化处理抑制了ROS的增加，阻断了ERK的激活和随后由这些刺激引起的心脏肥大。结论：这些数据表明，ROS介导了ET-1或PE诱导的成年大鼠心肌细胞心肌肥大的信号转导。

OBJECTIVES : We analyzed the regulatory function of reactive oxygen species (ROS) on the hypertrophic signaling in adult rat cardiac myocytes.BACKGROUND : The ROS regulate mitogenic signal transduction in various cell types. In neonatal rat cardiac myocytes, antioxidants have been shown to inhibit cardiac hypertrophy, and ROS are suggested to modulate the hypertrophic signaling. However, the conclusion may not reflect the situation of mature heart, because of the different nature between neonatal and adult cardiac myocytes.METHODS : Cultured adult rat cardiac myocytes were stimulated with endothelin-1 (ET-1) or phenylephrine (PE), and intracellular ROS levels, the activities of mitogen-activated protein kinases (MAPKs ; ERK, p38, and JNK), and 3H-phenylalanine incorporation were examined. We also examined the effects of antioxidant pretreatment of myocytes on MAPK activities and cardiac hypertrophy to analyze the modulatory function of redox state on MAPK-mediated hypertrophic signaling.RESULTS : The ROS levels in ET-1 or PE-stimulated myocytes were maximally increased at 5 min after stimulation. The origin of ROS appears to be from NADH/NADPH oxidase, because the increase in ROS was suppressed by pretreatment of myocytes with NADH/NADPH oxidase inhibitor diphenyleneiodonium. Extracellular signal-regulated kinase (ERK) activity was increased by the stimulation of ET-1 or PE. In contrast, p38 and c-Jun-N-terminal protein kinase (JNK) activities did not change after these stimulation. Antioxidant treatment of myocytes suppressed the increase in ROS and blocked ERK activation and subsequent cardiac hypertrophy induced by these stimuli.CONCLUSIONS : These data demonstrate that ROS mediate signal transduction of cardiac hypertrophy induced by ET-1 or PE in adult rat cardiac myocytes.