摘要
持久激动β肾上腺素受体(β adrenergic receptor,βAR)可导致病理性心肌肥厚,但其机制尚不明确。本研究观察抗氧化剂N-乙酰半胱氨酸(N-acetylcysteine,NAC)对异丙肾上腺素(isoproterenol,ISO)诱导的心肌肥厚大鼠的心肌氧化应激水平及钙/钙调蛋白依赖性蛋白激酶II(calcium/calmodulin-dependent protein kinase II,CaMKII)表达的影响,探讨βAR持久激动诱发心肌肥厚机制中CaMKII和氧化应激的作用。健康雄性Wistar大鼠,随机分成4组:正常对照组(CTRL),ISO处理组(ISO),正常NAC组(CTRL+NAC)和ISO处理+NAC组(ISO+NAC),每组6只。ISO及ISO+NAC组动物每天腹腔注射3mg/kgISO,CTRL及CTRL+NAC组腹腔注射相同体积的生理盐水;CTRL+NAC及ISO+NAC组动物每日自由饮用含15g/LNAC的饮用水。每周用无创动脉血压仪检测鼠尾动脉血压,连续2周;以心重指数(HW/BW)和左心室组织HE染色检测心肌肥厚情况;荧光测定法检测心肌线粒体活性氧(reactive oxygen species,ROS)水平;Western blot检测左室心肌NADPH氧化酶4(NADPH oxidase 4,NOX4)以及有活性的CaMKII(p-CaMKII/CaMKII)的表达变化。结果显示,与CTRL组相比,ISO组大鼠出现明显的心肌肥厚,心肌线粒体ROS水平升高(P<0.05),心肌组织NOX4和p-CaMKII的表达均显著增加(分别为CTRL组的1.4倍和1.6倍,P<0.05);NAC显著改善了ISO诱导的心肌肥厚,降低了ISO诱导的心肌线粒体ROS过度生成(P<0.05vsISO),有效抑制了ISO诱发的NOX4及p-CaMKII表达上调(P<0.05vsISO);CTRL+NAC组各项指标与CTRL组大鼠无差异;各组动物尾动脉血压亦无显著性差异。上述结果提示,氧化应激和CaMKII在βAR持久兴奋诱发心肌肥厚机制中起重要作用,NAC可以通过抑制心肌细胞线粒体及NADPH氧化酶应激途径降低氧化应激水平,抑制CaMKII激活,从而改善βAR持久激动引起的心肌肥厚。
Sustained activation of β adrenergic receptor （βAR） leads to pathologic cardiac hypertrophy. However, the related mecha- nisms still remain unclear. In this study, we observe how N-acetylcysteine （NAC） affects the oxidative stress and calcium/calmodulin- dependent protein kinase Ⅱ （CaMKⅡ） expression in heart of isoproterenol （ISO）-stimulated rats, and investigate whether oxidative stress and CaMKII contribute to the development of sustained βAR-stimulated cardiac hypertrophy. Healthy male Wistar rats were randomly separated into 4 groups： control （CTRL）, ISO-treated （ISO）, control with NAC supplement （CTRL＋NAC） and ISO-treatedwith NAC supplement （ISO＋NAC） groups （6 rats in each group）. Systolic blood pressure （SBP） was measured in awake rats with the tail-cuff method every week for two weeks. Heart weight/body weight ratio （HW/BW） and HE staining were used for the detection of myocardial hypertrophy. Myocardial mitochondrial reactive oxygen species （ROS） levels were measured by DCF fluorometry. The expressions of activated-CaMKII （p-CaMKⅡ/CaMKⅡ） and NADPH oxidase 4 （NOX4）were determined by Western blot analysis. The results showed that ISO-treated （i.p., daily 3 mg/kg, 2 weeks） rats developed an obvious cardiac hypertrophy as expressed by increases of HW/BW and myocyte cross-section area. Cardiac mitochondrial ROS level was significantly enhanced in ISO group as compared to CTRL group （P 〈 0.05）. The expressions ofNOX4 and p-CaMKⅡ in ISO group were also up-regulated as compared to CTRL group （1.4 and 1.6 times of CTRL, respectively, P 〈 0.05）. NAC supplement significantly suppressed the hypertrophic development of heart in ISO-stimulated rats. The cardiac mitochondrial ROS level showed a significant decrease in rats of ISO＋NAC group （P 〈 0.05 vs ISO）. In accordance with this, ISO＋NAC group rats also-showed marked reductions in the expressions of NOX4 and p-CaMKⅡ/CaM- KⅡ compared to ISO group rats （P 〈 0.05）. There were no significant differences of the detected indices between the rats from CTRL＋NAC and CTRL groups. SBP showed no differences among four groups. These results suggest that both oxidative stress and CaMKII play important roles in sustained βAR-stimulated cardiac hypertrophy. NAC may suppress ISO-induced cardiac hypertrophy by down-regulating the expression of activated-CaMKⅡ, and by reducing the level of oxidative stress originated from mitochondria and NADPH oxidase pathways.
出处
《生理学报》
CAS
CSCD
北大核心
2013年第1期1-7,共7页
Acta Physiologica Sinica
基金
supported by High School Science and Technology Fund Planning Project of Tianjin Municipality,China(No.20060206)
the Scientific Research Fund of Tianjin Medical University,China(No.2011ky33)
