大鼠慢性缺氧高二氧化碳肺动脉高压模型可溶性鸟苷酸环化酶的表达

目的　观察大鼠慢性缺氧高二氧化碳 (CO2 )肺动脉高压模型肺动脉可溶性鸟苷酸环化酶 (sGC)的表达及其活性。方法　SD大鼠 2 0只 ,随机分为 2组 ,每组 10只。A组 :慢性缺氧高CO2肺动脉高压模型组 ,大鼠置于常压低氧高CO2 饲养舱 ,舱内氧浓度维持在 ( 10 0± 0 5 ) % ,CO2 浓度为 6 %～ 7% ,每天 8h。B组 :健康对照组 ,大鼠室温下常规饲养。免疫组化观察 2组大鼠肺中小动脉sGCα1、β1亚基蛋白的表达 ,原位杂交观察肺中小动脉sGCα1亚基mRNA的表达。酶动力学分析肺组织sGC酶活性。结果　A组大鼠平均肺动脉压、右心室 / (左心室 +室间隔 )比值、右心室 /体重比值明显高于B组 (P值均 <0 0 1) ,A组肺中小动脉sGCα1、β1亚基蛋白及α1亚基mRNA表达与B组相比逐渐减弱 (P值均 <0 0 1) ,硝普钠激活的sGC酶活性及肺组织基础sGC酶活性A组明显低于B组。结论　慢性缺氧高CO2 肺动脉高压时肺中小动脉sGCmRNA、蛋白表达以及酶活性均受抑制

Study on soluble guanylate cyclase in pulmonary hypertension rat model

OBJECTIVE: To investigate the mRNA and protein expressions of soluble guanylate cyclase (sGC) and its enzyme activity in pulmonary hypertension rat model which was reproduced by hypoxia and hypercapnia. METHODS: Male Sprague-Dawley rats were randomly divided into hypoxic and hypercapnic group (HH group) and control group (C group). The protein expressions of sGC alpha(1) and sGC beta(1) subunits in medial and small pulmonary arteries was measured by immunohistochemistry method with a polycolonal antibody.The mRNA expression of sGC alpha(1) subunit of lung tissue was detected by in situ hybridization using sGC oligonuclear probe. Basal sGC enzyme activity and sodium nitroprusside (SNP)-stimulated sGC activity in lung homogenates were assayed with enzyme kinetic analysis. RESULTS: The mean pulmonary artery pressure (mPAP), the ratio of right ventricle/left ventricle + septum [RV/(LV + S)] and the ratio of right ventricle/body weight (RV/BW) were significantly higher in HH group than those in C group. The protein expressions of sGC alpha(1) and sGC beta(1) subunits and mRNA expressions of sGC alpha(1) subunit were significantly decreased in the small and medium pulmonary arteries in HH group as compared with those in C group (P < 0.01). Basal sGC enzyme activity in HH group (32.03 +/- 7.17 pmol cGMP synthesized.mg protein(-1).min(-1)) was significantly lower than that in C group (114.76 +/- 18.37 pmol cGMP synthesized.mg protein(-1).min(-1), P < 0.01). The SNP significantly increased the sGC enzyme activity but the SNP-stimulated sGC enzyme activity of lung homogenates in HH group was significantly lower than that in C group (P < 0.01). CONCLUSIONS: The mRNA and protein expressions of sGC subunits and their enzyme activities in lung tissue of pulmonary hypertension rat model were reduced.