氧化应激对Dahl盐敏感性高血压大鼠主动脉Rho激酶的直接作用  

Direct Effect of Oxidative Stress on Rho Kinase in the Aorta of Hypertensive Salt-sensitive Rats

作　　者：张玲[1] 多耀祥[1] 刘艳霞[2] 刘奔[1] 周明生[3] 

机构地区：[1]天津医科大学基础医学院生理学教研室,天津300070 [2]天津医科大学基础医学院药理学教研室,天津300070 [3]美国迈阿密大学米勒医学院血管生物学研究所高血压/肾病研究室

出　　处：《中华高血压杂志》2009年第9期791-795,共5页Chinese Journal of Hypertension

基　　金：教育部科学技术研究重点项目(207009)

摘　　要：背景氧化应激与原发性高血压的发生密切相关。近年来研究表明氧化应激信号分子(ROS)可导致高血压动物血管功能紊乱,最近证明RhoA及其下游效应分子Rho激酶参与高血压发病,但参与机制还有许多不明之处。目的观察抗氧化剂N乙酰半胱氨酸(NAC)对Dahl盐敏感性(DSS)高血压大鼠主动脉Rho/Rho激酶(ROK)表达的影响,探讨盐敏感性高血压发病机制中ROS与Rho信号通路的关系。方法DSS高血压大鼠随机分为4组:正常饮食组;高盐饮食组(高盐组);高盐饮食辅以NAC治疗组(高盐+NAC组);正常饮食辅以NAC治疗组(正常饮食+NAC组),每组6只。每周测定鼠尾动脉血压,共4周;收集24 h尿,处死后取主动脉组织标本。DCF荧光法检测尿中氧化应激生物标志物过氧化氢(H2O2)水平;光泽精化学发光法检测主动脉超氧阴离子生成量;RT-PCR及Western Blot检测主动脉RhoA、ROK mRNA及蛋白表达。结果高盐饮食组与正常饮食组相比,血压明显升高[(219.7±5.3)比(152.8±3.8)mmHg,P<0.01],24 h尿中H2O2排出量显著增加[(663.8±67.7)比(18.9±4.5)nmol/d,P<0.01];高盐饮食大鼠主动脉超氧阴离子生成量较正常大鼠增多[(12.8±0.5)比(6.9±0.3)counts/(min.mg),P<0.01],主动脉ROK mRNA和蛋白表达亦明显增加(P<0.01)。NAC显著降低了高盐饮食大鼠血压[(161.8±2.9)mmHg,P<0.01]、尿H2O2排出量[(243.0±49.3)nmol/d,P<0.01]和主动脉超氧阴离子的生成[(7.7±0.6)counts/(min.mg),P<0.01],抑制了ROKmRNA和蛋白的过表达。但是,作为ROK上游的小G蛋白,RhoA表达在4组大鼠间并无差异(P>0.05)。结论DSS高血压大鼠主动脉ROK表达增加,表明Rho信号参与盐敏感性高血压的发生发展;RhoA可能不是此类高血压动物ROK激活的决定因素。NAC阻断后ROK表达显著下调,其机制可能与ROS的诱导作用降低有关,ROS可能作为上游信号直接参与DSS高血压大鼠ROK的激活。Background Recent studies demonstrated the role of reactive oxygen species （ROS） in vascular dysfunction in hypertension; Studies also reveal RhoA and its downstream effector, Rho kinase, involved in the development of hypertension, however, the mechanism remained unclear. Objective To study the antioxidant effect of N acetylcysteine （NAC） on the expression of Rho/Rho kinase （ROK） in the aorta of hypertensive saltsensitive rats and investigate effect of ROS on Rho/ROK pathway in the development of salt-sensitive hypertension. Methods Dahl salt-sensitive （DSS） rats were randomly assigned to receive a normal （N） diet; a high-salt （HS） diet; a high-salt diet plus NAC supplement（HS-t-NAC）, or a normal diet plus NAC supplement（N＋ NAC） for 4 weeks. SBP was measured in awake rats with the tail-cuff method every week. 24 h urine was gathered and aorta tissues were obtained. Urinary H2O2 levels were measured by DCF fluorometry; Vascular superoxide production was determined using Luciginin chemiluminescence; Expression of RhoA, Rho kinase is accessed by the methods of RT - PCR and Western Blot. Results Compared with normal diet rats , high salt diet Dahl rats achieved markedly elevated systolic arterial pressure[（219.7±5.3） vs （152.8±3.8） mmHg, P〈0.01], urinary excretion of hydrogen peroxide （H2O2）[（663.8±67.7） vs （18.9±4.5） nmol/d, P〈0.01], and increased superoxide productionS（12.8±0.5）vs （6.9±0. 3） counts/（min · mg）, P〈0. 01] in aorta, as well as Rho kinase expression of aorta at the levels of mRNA and protein（P〈0.01）. NAC reduced the increases in SBP[（161.8± 2.9）mmHg, P〈0.01] and counteracted the elevation of urinary of H2O2 [（243.0 ± 49.3）nmol/d, P〈0.01], aortic superoxide production [（7. 7±0. 6） counts/（min · mg）, P〈0.01] in rats of HS＋NAC group. The overexpression of ROK mRNA and protein of aorta were also markedly downregulated in high-salt-loaded DSS rats by NAC supplement. But no obvious changes of expr

关 键 词：RHO激酶 活性氧簇 原发性高血压 Dahl盐敏感性大鼠 N乙酰半胱氨酸 

分 类 号：R544.1[医药卫生—心血管疾病]