【作者】 黄兴林；

【导师】 高兴亚； 朱国庆；

【作者基本信息】 南京医科大学 ， 生理学， 2008， 硕士

【摘要】 高血压病是严重危害人类健康的常见病,主要特征为总外周阻力持续增高导致血压异常升高,并伴随着心脏和血管等结构性变化。其中,血管重构在高血压病的发生和病程发展中起关键性作用。目前,下肢动脉血管重构（vascular remodeling,VR）已成为国际上对高血压及其预后进行分析研究的热点,针对血管重构发生机制以逆转血管重构是防治高血压及其靶器官损害的重要靶标。高血压时血管紧张素Ⅱ（angiotensinⅡ,AngⅡ）作为肾素—血管紧张素系统（rennin-angiotensin system,RAS）的主要递质,可诱导血管重构,内皮和平滑肌细胞血管紧张素Ⅰ型受体（angiotensin type 1 receptor,AT₁）表达增加,对缩血管物质的反应增强,这在高血压及其并发症的发生和维持中起关键性作用。活性氧（reactive oxygen species,ROS）作为细胞信号和调控的主要参与者,其生成与代谢的改变,参与了多种病理过程。我们近年研究发现中枢ROS介导了AngⅡ心交感传入反射增强、肾交感神经放电增加和血压增高效应。目前ROS和AngⅡ的关系成为人们关注的焦点。本研究以肾血管型高血压大鼠（renalhypertensive rats,RHR）股动脉为模型,选择国际上临床研究关注的下肢动脉为观察对象,探讨股动脉平滑肌中ROS是否调控血管基础张力,是否介导AngⅡ引起的缩血管效应以及介导AngⅡ缩血管效应的ROS是否主要来源于NAD（P）H氧化酶作用。确定ROS在高血压病血管重构中的功能性变化,为防治高血压病提供新思路和理论依据。实验在RHR大鼠的离体去肉皮股动脉环上进行,以假手术（Sham）大鼠离体去内皮股动脉环作为对照,记录股动脉环平滑肌张力。以平滑肌张力变化值作为评价缩血管效应的指标。用硫代巴比妥酸法测定血管环平滑肌中丙二醛（MDA）水平,并用化学发光法测定血管环中超氧阴离子（O₂^-）水平,作为评价ROS水平的指标。主要研究结果如下:1、AngⅡ引起RHR和Sham大鼠股动脉环平滑肌张力显著增加且具有明显的剂量效应关系;与Sham组相比,同等剂量的AngⅡ在RHR大鼠引起的缩血管效应更加明显。AT₁受体拮抗剂losartan引起RHR大鼠血管张力轻度降低,但对Sham大鼠无显著影响。losartan预处理可以完全阻断AngⅡ的缩血管效应。2、超氧阴离子清除剂tempol和tiron轻度降低RHR大鼠股动脉环平滑肌张力,但对Sham大鼠无显著影响;SOD抑制剂DETC增强RHR和Sham大鼠股动脉环平滑肌张力,且在RHR大鼠引起的血管张力增加更加明显。Tempol和tiron预处理阻断RHR和Sham大鼠AngⅡ缩血管效应,而DETC预处理增强RHR组AngⅡ缩血管效应,但对Sham大鼠无显著影响。3、NAD（P）H氧化酶抑制剂apocynin轻度降低RHR和Sham大鼠股动脉环平滑肌张力,其对RHR大鼠平滑肌张力的抑制作用更加明显。apocynin预处理完全阻断RHR和Sham大鼠AngⅡ引起的缩血管效应。4、RHR大鼠股动脉环平滑肌中MDA和超氧阴离子水平显著升高,AngⅡ可使其水平进一步升高,且RHR大鼠升高效应更加明显;AT₁受体拮抗剂losartan对MDA和超氧阴离子水平无直接影响,但losartan预处理阻断RHR和Sham大鼠AngⅡ引起的平滑肌中MDA和超氧阴离子水平升高效应。本研究表明高血压大鼠股动脉血管平滑肌中ROS调控血管张力,并介导AngⅡ兴奋AT₁受体引起的缩血管效应,NAD（P）H氧化酶是ROS生成的重要起源,血管平滑肌中AngⅡ与ROS异常在高血压大鼠股动脉平滑肌功能性血管重构中起重要作用。更多还原

【Abstract】 Hypertension is one of the most common cardiovascular diseases. The incidence of the disease was as high as 18.8%and increased very quickly.However,the mechanism of hypertension is not completely known.The enhanced tension of vascular is a hallmark of hypertension and the degree of vascular remodeling（VR）is prognostic for survival in the hypertensive state.The tension of vascular,which is enhanced in the hypertensive state,contributes to an increase in VR in the hypertensive state.Previous studies suggested the abnormal action of AngⅡand AT₁ receptor in vascular smooth muscle（VSM）played an important part in vasoconstriction in hypertension.However,the mechanism responsible for the enhancement of the tension induced by AngⅡin VSM is not well understood.In the present study,we investigated the role of ROS in the regulatory effect of AngⅡon vasoconstriction and further elucidated the vascular mechanism responsible for modulation of the blood pressure.It will lay a foundation in finding new drugs for management of hypertension.The study was carried out on isolated rings of femoral artery with endothelium removal in renal hypertensive rats（RHR）and those age-matched controls（Sham）.Tension of VSM was recorded.Vascular reactivity to vasoactive substances was evaluated by the change of tension in rings of femoral artery.Superoxide anion level was measured with lucigenin-enhanced chemiluminescent method.Malondialdehyde （MDA）was determined by the thiobarbituric acid（TBA）spectrometric method,which indirectly indicated the ROS level in VSM.The primary findings were as follows.1.Study on the role of ROS in modulating of the tension of VSM and mediating the effect of AngⅡon vasoconstriction.Superoxide scavenger tempol or tiron showed a weak inhibitory effect on the enhanced tension in RHR and had no significant effect of the tension in Sham.Pretreatment with tempol or tiron significantly blocked the enhanced tension of VSM induced by AngⅡin both RHR and Sham. Superoxide dismutase（SOD）inhibitor diethyldithio-carbamic acid （DETC）augmented the tension of VSM in RHR,but did not significantly potentiate the effect of AngⅡon vasoconstriction in both RHR and Sham.Incubation of AngⅡ,which elicited vasoconstriction,significantly increased MDA and superoxide anion levels in HR,and these effects were abolished by pretreatment with AT₁ receptor antagonist losartan in both RHR and Sham. 2.Study on the major source of the ROS in modulating the enhanced tension of VSM and mediating the vasoconstriction of AngⅡin RHR.NAD（P）H oxidase inhibitor apocynin showed a weak inhibitory effect on the enhanced tension in RHR and had no significant effect of the tension in Sham.Pretreatment with apocynin significantly blocked the enhanced tension induced by AngⅡin both RHR and Sham.In conclusion,the ROS in VSM are involved in the modulation of the enhanced tension of the VSM and contributed to the excitory effect of AngⅡon the vasoconstriction in RHR,the NAD（P）H oxidase is the major source of the ROS.更多还原