Shimojo Nobutake, Jesmin Subrina, Zaedi Sohel, Soma Masaaki, Kobayashi Tsutomu, Maeda Seiji, Yamaguchi Iwao, Goto Katsutoshi, Miyauchi Takashi
Cardiovascular Division, Department of Internal Medicine, Institute of Clinical Medicine, University of Tsukuba, Ibaraki 305-8575, Japan.
Exp Biol Med (Maywood). 2006 Jun;231(6):913-8.
Cardiomyocytes release (or metabolize) several diffusible agents (e.g., nitric oxide [NO], endothelin-1 [ET-1], and angiotensin II) that exert direct effects on myocyte function under various pathologic conditions. Although cardiac hypertrophy is a compensatory mechanism in response to different cardiovascular diseases, there can be a pathologic transition in which the myocardium becomes dysfunctional. Recently, NO has been found to be an important regulator of cardiac remodeling. Specifically, NO has been recognized as a potent antihypertrophic and proapoptotic mediator in cultured cardiomyocytes. We demonstrated that ET-1-induced hypertrophic remodeling in neonatal cardiomyocytes was arrested by pretreatment with eicosapentaenoic acid (EPA), a major component of fish oil. In some recent studies, EPA has demonstrated cardioprotective effects by modulating NO. This study investigated the changes in NO synthase (NOS) in ET-1-induced hypertrophied cardiomyocytes and in total levels of nitrates and nitrites. Ventricular cardiomyocytes were isolated from 2-day-old Sprague-Dawley rats and were cultured in D-MEM/Ham F12 supplemented with 0.1% fatty acid-free bovine serum albumin for 3 days. At Day 4 of culture, the cardiomyocytes were divided into three groups: control group, ET-1 (0.1 nM) group, and ET-1 pretreated with EPA (10 microM) group. NOS gene expression was evaluated 24 hrs after treatment using real-time polymerase chain reaction. Endothelial NOS (eNOS) mRNA expression was decreased in the ET-1 group compared with controls and was unchanged by pretreatment with EPA. mRNA expression of inducible NOS (iNOS) was significantly increased in ET-1-treated cardiomyocytes and was suppressed by EPA pretreatment. Neuronal NOS gene expression and total NO level did not exhibit a statistically significant change in any of the groups. There may be some interaction between ET-1, eNOS, and iNOS in ET-1-induced and EPA-regressed hypertrophied cardiomyocytes that suppress iNOS expression without modulating total NO level or eNOS gene expression.
心肌细胞释放（或代谢）多种可扩散因子（如一氧化氮[NO]、内皮素-1[ET-1]和血管紧张素II），这些因子在各种病理条件下对心肌细胞功能产生直接影响。虽然心肌肥大是对不同心血管疾病的一种代偿机制，但可能会出现病理性转变，即心肌功能失调。最近，NO被发现是心脏重塑的重要调节因子。具体而言，NO已被公认为培养心肌细胞中一种强大的抗肥大和促凋亡介质。我们证明，用鱼油的主要成分二十碳五烯酸（EPA）预处理可阻止ET-1诱导的新生心肌细胞肥大重塑。在最近的一些研究中，EPA已通过调节NO显示出心脏保护作用。本研究调查了ET-1诱导的肥大心肌细胞中一氧化氮合酶（NOS）的变化以及硝酸盐和亚硝酸盐的总水平。从2日龄的Sprague-Dawley大鼠中分离出心室心肌细胞，并在补充有0.1%无脂肪酸牛血清白蛋白的D-MEM/Ham F12中培养3天。在培养的第4天，将心肌细胞分为三组：对照组、ET-1（0.1 nM）组和用EPA（10 microM）预处理的ET-1组。使用实时聚合酶链反应在处理后24小时评估NOS基因表达。与对照组相比，ET-1组中内皮型NOS（eNOS）mRNA表达降低，而EPA预处理未使其改变。诱导型NOS（iNOS）的mRNA表达在ET-1处理的心肌细胞中显著增加，并被EPA预处理所抑制。神经元型NOS基因表达和总NO水平在任何组中均未表现出统计学上的显著变化。在ET-1诱导和EPA逆转的肥大心肌细胞中，ET-1、eNOS和iNOS之间可能存在一些相互作用，这种相互作用可抑制iNOS表达，而不调节总NO水平或eNOS基因表达。
