体外反搏对高胆固醇血症猪颈动脉内膜形态和功能的影响

目的 探讨长期体外反搏对高胆固醇血症猪颈动脉内膜形态和内皮依赖血管舒张功能的影响.方法 18头雄性乳猪被随机分为3组,每组6只.用喂养高脂饲料乳猪复制高胆固醇血症模型(高脂饲养组);采用增强型体外反搏(EECP)治疗模型动物36 h(EECP组);以正常饲养组作为对照.取各组动物颈总动脉血管.用扫描电镜和透射电镜观察颈动脉内膜的形态,并测定离体颈动脉血管环对不同浓度梯度乙酰胆碱(Ach)的舒张反应.结果 扫描电镜下观察高脂饲养组血管内皮细胞排列紊乱,内皮细胞有明显脱落,部分细胞胞膜皱缩.体积明显减小,符合凋亡细胞的外形特征;EECP组血管内皮细胞排列紊乱的情形明显减轻,内皮细胞大小不一的程度减轻,皱缩脱落细胞较高脂饲养组明显减少.透射电镜下观察高脂饲养组血管内皮细胞凋亡、脱落,内膜破损明显,平滑肌细胞侵入和增生,泡沫细胞形成;EECP组内皮细胞呈梭形,内皮完整,内皮与内皮下结构连接紧密,平滑肌细胞轻度增生,少见泡沫细胞.在10-8～10-5mol/L Ach时,高脂饲养组和EECP组的血管舒张率较正常饲养组显著降低(P均＜0.05);在10-7～10-5mol/L Ach时,EECP组的血管舒张率较高脂饲养组明显提高(P均＜0.05).结论 高胆固醇血症动物颈动脉内皮超微结构改变提示有动脉粥样硬化形成,内皮依赖血管舒张功能明显受损;长期EECP干预可以显著改善内皮结构损伤和内皮依赖血管舒张功能,这可能是其发挥抗动脉粥样硬化作用的机制之一.

Effect of external counterpulsation on morphological damage of endomembrane and endothelium-dependent vasodilatation in the carotid arteries in hypercholesterolemic pigs

Objective To explore the effect of long-term enhanced external counterpulsation (EECP) on morphological damage of endomembrane and endothelium-dependent vasodilatation of the carotid arteries of hypercholesterolemic pigs.Methods Eighteen male infant pigs were randomly divided into three groups according to the contents of their diet: the normal control group (n=6),the high-cholesterol feeding control group (n=6) and EECP group (n=6).Porcine model of hypercholesterolemia was reproduced by feeding animals with high-cholesterol diet.After completion of EECP treatment for 36 hours in EECP group,carotid arterial rings were harvested from all animals.Both scanning and transmission electron microscopy was employed to observe the changes in morphology of their endomembrane. At the same time, their vasodilatation response to variant dose of acetylcholine (Ach) was detected. Results The surface of endothelium in the normal control group was smooth,and endothelial cells were in regular streamline array,and they were almost in same size,attaching closely to matrix without smooth muscle cell proliferation and lipid infiltration in intima.In contrast,the endothelial cells of hypercholesterolemic pigs were in irregular array,with marked desquamation,resulting in loose linkage.Smooth muscle ceils were found to invade into intimal layer and proliferated,and foam cells could also be found in intimal layer.In hypercholesterolemic pigs treated with EECP,slight intimal damage was found.In addition,with Ach dose of 10-8 mol/L to 10-5 mol/L,endothelium-dependent vasodilatation ratio in hypercholesterolemic pigs with or without EECP treatment,was significantly lower than that of the normal control group (all P＜ 0.05). However,endothelium-dependent vasodilatation ratio in pigs with EECP treatment was obviously higher compared with hypercholesterolemic pigs without EECP treatment with the dosage of Aeh concentration ranged from 10-7 mol/L to 10-5 mol/L (all P＜0.05).Conclusion Long-term EECP ameliorates both the morphological damage and the impaired endothelium-dependent vasodilatation function resulting from hypereholesterolemia,contributing to prevention of atherosclerosis.