氯沙坦对自发性高血压大鼠阻力血管结构的影响

目的探讨氯沙坦（Losartan）对自发性高血压大鼠（SHR）阻力血管结构的影响,并观察在高血压血管壁增厚的过程中血管紧张素Ⅱ(AngⅡ)所起的作用。方法采用6周龄雄性SHR20只,随机分为Losartan治疗组（SHRlos）和对照组（SHR）。另选同系雄性6周龄WKY鼠10只作为正常对照组。6周龄SHRlos给予Losartan30mg/kg/d,溶于饮水灌胃治疗17周。颈动脉插管,心电血流动力学监护仪测定动脉收缩压,应用计算机图象分析,计算血管壁腔面积比,用光镜和透射电镜观察SHR肠系膜动脉三级分支结构的变化;血浆放免法测肾素活性和AngⅡ含量。结果（1）动脉收缩压（SBP）治疗结束后,SHR

Effects and Mechanisms of Losartan on the Structure of Resistant Vessel in Spontaneously Hypertensive Rat

Objective To evaluate the effects of Losartan on systolic blood pressure,the structure of resistant vessel and the changes of plasma angiotensinⅡ in spontaneously hypertensive rats (SHR). Methods six weeks male SHR and WKY were divided into three groups at random: SHR losartan group、SHR control group、WKY normal control group. Losartan 30 mg.kg-1.d-1 was adm inistered by gavage to rats in SHR Losartan group. After 17 weeks treatment, Wall-to-lumen ar ea ratios (W/L)of mesenteric arteries (3 rd grade branch ) were calculated by computer image analysis system. Systolic blood pressure(SBP) were measured. The level of vessel hypertrophy was assessed by means of transmission electron microscope. The plasma renin activity and AngⅡlevel was determined by RIA method. Results (1) After 17 weeks treatment, the blood pressure of SHR losartan group was decreased compared with SHR control group (P<0.05). (2) Th e W/L in SHR losartan group was significantly decreased compared with SHR control group (P<0.01). There was no remarkable difference in W/L between SHR losa rtan and WKY group(P>0.05).While the W/L in SHR losar tan group is still remain in a higher level than that of WKY rats(P<0.05). The ultrastructures of mesenteric arteries in SHR losartan group were similar with those of WKY normal group; however, ultrast ructure change in mesenteric arteries in SHR control group were pronouncedly. (3) The plasma renin activities had no significant differences (P>0.05) be tween WKY normal group and SHR control group. The plasma renin activities in SHR losartan group increased compared with SHR control group (P<0.05). AngⅡ level in SHR losartan group significantly increased compared with SHR control group (P<0.01). The AngⅡ level in SHR losartan group was hig her than that in WKY normal group (P<0.05). Conclusion These results indicated that long-term treatment with Losartan effectively reduced blood pressure、attenuated and regressed the resist ant vessel hypertrophy during the development of hypertension in SHR.