止血带休克后主动脉收缩反应性及RAS成分的变化

 目的: 通过观察止血带休克(tourniquet shock,TS)后主动脉收缩反应性及肾素-血管紧张素系统(renin-angiotensin system,RAS)的变化,探讨RAS稳态失衡在止血带休克后主动脉低反应性及损伤中的作用。方法: 8月龄C57BL/6的雄性小鼠,分为对照组及6个模型组,每组6只。模型组进行止血带套扎双后肢阻断血流,2 h后解套扎进行再灌注,分别于再灌注10 min、1 h、2 h、4 h、6 h和12 h后处死,对照组不进行套扎与再灌注,其余操作同模型组;多普勒血流仪测定肢体血流,颈动脉插管法测定平均动脉压(MAP),离体血管张力测定仪测定主动脉收缩反应性,HE染色结合透射电镜评价血管形态学损伤;Western blot检测血管组织中血管紧张素Ⅱ 1型受体(AT1受体)、血管紧张素(1-7)受体(Mas受体)、血管紧张素转换酶(ACE)和ACE2蛋白的表达。采用ELISA检测血清中血管紧张素Ⅱ(AngⅡ)和血管紧张素(1-7)Ang(1-7)]的含量。结果: 与对照组相比,模型组出现下述变化:(1)随着再灌注时间的延长血流量逐渐减少;MAP在再灌注10 min明显升高,随后逐渐降低;血管对去甲肾上腺素的反应性在再灌注10 min升高随后下降,再灌注4 h的血管反应性最低;形态学损伤评分随再灌注时间延长逐渐增高;(2)主动脉AT1受体与ACE2蛋白表达逐渐下降,Mas受体与ACE蛋白表达逐渐升高;(3)血清中AngⅡ的含量整体呈升高趋势,Ang(1-7)的含量整体呈降低趋势。结论: 主动脉收缩反应性在休克初期暂时升高,随后降低,其发生机制可能与血管形态学损伤及RAS失衡有关。

Changes of aortic contractile reactivity and RAS components after tourniquet shock

AIM: To investigate the role of renin-angiotensin system(RAS) disequilibrium in hyporeactivity and injury of aorta after tourniquet shock(TS) by observing the changes of aortic contractile reactivity and RAS components after TS. METHODS: Male C57BL/6 mice(8 months old) were divided into 7 groups including control group and 6 model groups. The mice in model groups were sacrificed at reperfusion of 10 min, 1 h, 2 h, 4 h, 6 h and 12 h. The mice in control group were not subjected to tourniquet ligation. The Doppler flowmetry was used to determine the limb blood flow. The carotid artery catheter was applied to detect the blood pressure. The isolated vascular tension tester was available to measure the reactivity of the aorta. HE staining combined with transmission electron microscopy was used to evaluate the morphology of injured aortas. The protein expression of AT1 receptor, Mas receptor, ACE and ACE2 was measured by Western blot. The serum contents of Ang Ⅱ and Ang(1-7) were detected by ELISA. RESULTS: Compared with control group, the blood flow in model groups decreased gradually with the prolongation of reperfusion time. The blood pressure increased at 10 min after reperfusion, and then decreased gradually. Accordingly, vascular reaction to norepinephrine(NE) increased at 10 min and then descended. The vascular reactivity reached the lowest level at 4 h. Morphological injury score increased gradually. Vascular AT1 receptor and ACE2 proteins were reduced, while Mas receptor and ACE proteins were up-regulated compared with control group. The content of Ang Ⅱ in the serum elevated, while the content of Ang(1-7) was reduced. CONCLUSION: The mechanism of aortic reaction to NE increased temporarily in the early stage of shock and then decreased. It may be related to the morphological injury of aorta and the imbalance of RAS.