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目的:探讨氯沙坦(losartan)对自发性高血压大鼠(spontaneously hypertensiverat,SHR)急性脑梗死保护作用的动脉压力感受性反射(arterial baroreflex,ABR)机制。方法:灌胃给予氯沙坦2周,测定大鼠血流动力学指标及BRS(ABR功能用动脉压力感受性反射敏感性,baroreflex sensitivity)值。采用大脑中动脉(middle cerebral arterial,MCA)栓塞的方法诱发急性脑梗死,24h后取脑组织,切片、染色,观察急性脑梗死面积;孤束核(nucleus of solitary tract,NTS)分别微量注射血管紧张素Ⅱ(angiotensionⅡ,AngⅡ)及小剂量氯沙坦,测定大鼠血流动力学指标及BRS值,采用MCA栓塞的方法诱发急性脑梗死,观察药物对急性脑梗死的影响。结果:与对照组相比,灌胃给予氯沙坦后大鼠ABR功能改善,脑梗死面积显著降低(P<0.05)。孤束核微量注射AngⅡ可明显升高动物血压,降低BRS值;孤束核微量注射氯沙坦后在不改变血压的情况下可以使ABR功能明显改善(P<0.05),减轻脑梗死损伤(P<0.05)。结论:氯沙坦改善了ABR的敏感性,从而对急性脑梗死起防治作用,孤束核可能是其作用部位。
Objective: To investigate the mechanism of arterial baroreflex (ABR) of losartan on the protection of spontaously hypertensive rats (SHR) on acute cerebral infarction. Methods: Losartan was given intragastrically for 2 weeks to determine the hemodynamics and BRS (baroreflex sensitivity) of BRS. Acute cerebral infarction was induced by middle cerebral artery occlusion (MCA), and brain tissue was sectioned and stained 24 hours later. The area of acute cerebral infarction was observed. Nucleus of solitary tract (NTS) Angiotensin Ⅱ (AngⅡ) and low-dose losartan were used to measure the hemodynamics and BRS in rats. The acute cerebral infarction was induced by MCA embolization and the effect of drugs on acute cerebral infarction was observed. RESULTS: Compared with the control group, the ABR function of rats was improved after losartan was given by gavage. The area of cerebral infarction was significantly decreased (P <0.05). Microinjection of angiotensin Ⅱ into nucleus tractus solitarius can significantly increase blood pressure and decrease BRS. After injection of losartan in solitary tract, the function of ABR can be significantly improved (P <0.05) P <0.05). CONCLUSION: Losartan can improve the sensitivity of ABR and thus prevent and treat acute cerebral infarction. Nucleus tractus solitarius may be the site of its action.