卡托普利对动脉粥样硬化家兔血管内皮功能的保护作用及其机制

Protective effect and mechanism of captopril against endothelial dysfunction of thoracic aortas from atherosclerotic rabbits

目的探讨卡托普利对动脉粥样硬化(AS)家兔血管内皮功能和形态的保护作用及其机制。方法采用高脂、高胆固醇饲料饲养家兔制备AS模型的同时口服给予卡托普利8 mg·kg-1,每天1次,连续12周;HE染色观察血管组织形态,检测血清总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白(LDL)和高密度脂蛋白(HDL);高效液相色谱测定血清非对称性二甲基精氨酸(ADMA)浓度;用重组编码人类二甲基精氨酸-二甲胺水解酶2(hDDAH2)基因的腺病毒感染AS家兔离体胸主动脉环2 h,检测对乙酰胆碱累积浓度诱导的最大舒张反应(Emax)、半数有效量(EC50)及DDAH活性。结果与正常组比较,高脂模型家兔胸主动脉内膜和中膜增厚,血清TC,TG和LDL水平升高;血清ADMA浓度升高至(2.24±0.28)μmol·L-1(P<0.01);血管壁DDAH活性降至(0.048±0.007)U·g-1蛋白(P<0.01);Emax降低至(56±8)%(P<0.01),EC50升高至(158±52)nmol·L-1(P<0.01)。与AS模型组比较,卡托普利治疗组血管内膜增厚减轻,血脂无明显降低,血清ADMA浓度显著降低至(1.37±0.23)μmol·L-1(P<0.01),血管DDAH活性增加至(0.084±0.013)U·g-1蛋白(P<0.01),内皮依赖性血管舒张功能改善,Emax增加至(88±4)%(P<0.01),EC50降低至(90±35)nmol·L-1(P<0.01)。AS模型血管转染DDAH2基因后,血管Emax回升至(88±4)%,EC50降低至(98±42)nmol·L-1,DDAH活性升高至(0.112±0.017)U·g-1蛋白,与卡托普利治疗组相似。结论卡托普利对AS家兔血管形态和内皮功能具有明显保护作用,其机制可能与增加血管DDAH活性,降低内源性ADMA浓度有关。

OBJECTIVE To investigate the protective effects and mechanisms of captopril against vascular endothelial dysfunction and morphologic damage in atherosclerotic （AS） rabbits. METHODS The rabbits were fed a high-cholesterol and high-fat diets to induce AS, and at the same time treated with captopril （po 8 mg·kg-1） once daily for 12 week. The morphologic changes of thoracic aortas were observed by HE staining. Serum levels of total cholesterol （ TC）, triglycer- ides （TG）, low-density lipoprotein （LDL） and high-density lipoprotein （HDL） were determined. Serum levels of asymmetric dimethylarginine （ADMA） were assayed by high-pressure liquid chroma- tography. Recombinant human dimethylarginine dimethylaminohydrolase 2 （DDAH2） gene adenovi- ruses （AdSCMVhDDAH2） were ex vivo transferred to thoracic aortic tings from atherosclerotic rab- bits for 2 h. Endothelium-dependent maximal relaxation of aortic ring response to accumulative con- centrations of acetylcholine （ Emax ） , concentration for 50% of maximal effect （ EC50 ） and vascular DDAH activity were measured 24 h after transfection, respectively. RESULTS Compared with normal control group, the intima and media of thoracic aortas were thickened and serum lipid pro- files including TC, TG and LDL were obviously increased in rabbits fed high-fat diet. Serum ADMA levels were increased to （ 2.24 ＋- 0.28 ） μmol · L-1 （P 〈 0.01 ） and vascular DDAH activity was inhibited to （0. 048 ±0. 007） U· g-1 protein （P 〈 0.01 ） ; Emax was decreased to （56± 8 ） % （P 〈0.01 ） and EC50 was increased to （ 158 ±52） nmol·L-1 （P 〈0.01 ）. Treatment with captopril not only decreased vascular intima thickening and serum ADMA level to （ 1.37 ± 0.23 ） μmol· L- 1 （P 〈 0.01 ）, but also increased vascular DDAH activity to （0. 084± 0. 013 ） U · g-1 protein （P〈0.01） , Emax increased to （88±4） % （P〈0.01） and ECs0decreased to （90 ±35）nmol＇L-1 （ P 〈 0.01 ） without influence on serum lipid profiles. The similar results of Emax （ 88± 4 ） % , ECs0 （ 98± 42） nmol· L - 1 and DDAH activity （0.112 ± 0.017 ） U·g - 1 protein could also be observed when human DDAH2 gene was ex vivo transferred to isolated aortas from AS rabbits. CONCLUSION Captopril can protect against the injuries of vascular morphology and endothelial function in high-fat diet-induced AS rabbits, and the mechanisms may be involved in increase in DDAH activity and decrease in endogenous ADMA accumulation in vascular endothelium.