持续应用腺苷对大鼠低氧肺动脉高压的作用

目的 采用皮下微量注射泵持续注射腺苷14d,观察腺苷对低氧所致肺动脉高压的影响及作用机制.方法 将SD大鼠分成常氧组、低氧组和腺苷处理组,于低氧氧浓度(10.0±0.5)%]第7天皮下植人胶囊渗透压泵.腺苷组在低氧处理同时注射腺苷(100μg·kg-1·min-1);另两组泵内含等量生理盐水,持续14 do测尾动脉压力和肺动脉压力,取血浆检测肾素活性(RA)、血管紧张素Ⅱ(AngⅡ)、内皮素-1(ET-1)、NO水平.取肺动脉作免疫组化检测iNOS蛋白表达.结果 (1)低氧致肺动脉压力高于常氧组(P(0.01),而腺苷处理后肺动脉压力低于低氧组(P<0.01);(2)低氧组血浆ET-1水平明显高于常氧组(P<0.01),腺苷治疗组低于低氧组(P<0.01);低氧组血浆NO水平明显低于常氧组(P<0.01).腺苷治疗组高于低氧组(P<0.01);低氧组肺动脉血管iNOS蛋白表达高于常氧组,腺苷处理组肺动脉血管iNOS蛋白表达明显高于低氧组和常氧组(P<0.01);(3)低氧组血浆RA和AngⅡ水平明显高于常氧组(P<0.01),腺苷治疗组则明显低于低氧组(P<0.01).结论 外周持续腺苷给药可降低慢性低氧所致肺动脉高压,其机制与抑制体内肾素血管紧张素系统、内皮素水平,促进肺动脉iNOS表达和增高血浆NO水平有关.

Effects of continuous adenosine infusion on pulmonary hypertension in chronically hypoxic rats

OBJECTIVE: To observe the effects of continuous subcutaneous adenosine infusion on pulmonary hypertension in chronically hypoxic rats. METHODS: Twenty-four SD rats were randomized into normoxic group, hypoxic group and adenosine-treated hypoxic group. Hypoxic environment was simulated in a chamber filled with 10% oxygen and 90% nitrogen. After 7 days of hypoxia, adenosine were administered subcutaneously in the rats in adenosine-treated group at the rate of 100 microg kg(-1) min(-1) via an Alzet micro-osmotic pump for 14 days, while the pumps in the other two groups contained normal saline. After 21 days of hypoxia, pulmonary artery pressure and tail-cuff blood pressure were measured, with the plasma rennin activity (RA), angiotensin II (AngII), endothelin (ET)-1, and nitric oxide (NO) determined. Inducible nitric oxide synthase (iNOS) expression in the pulmonary artery of the rats was detected using immunohistochemical method. RESULTS: The mean pulmonary artery pressure (mPAP) was significantly higher in the hypoxic group than that in the normoxic group (P<0.01) and in the adenosine-treated group (P<0.01). Plasma ET-1 was significantly higher but plasma NO significantly lower in the hypoxic group than in the normoxic group (P<0.01) and the adenosine-treated group (P<0.01). iNOS expression in the pulmonary artery was higher in the hypoxic group than in normoxic group (P<0.01), and adenosine significantly increased iNOS expression in comparison with the normoxic and hypoxic groups (P<0.01). Plasma RA and AngII in the hypoxic group were significantly higher than those in the normoxic group (P<0.01) and the adenosine-treated (P<0.01). CONCLUSION: Adenosine administered by continuous subcutaneous infusion alleviates chronically hypoxia-induced pulmonary hypertension in rats, in which rennin angiotensin system, ET-1, and iNOS/NO play a role.