高肺血流量对肺血管结构及胱硫醚-γ-裂解酶基因表达的影响

目的：探讨高肺血流量所致肺动脉高压大鼠肺血管结构和内源性硫化氢体系的变化。方法：SD大鼠共16只，随机分为分流组及对照组。对分流组大鼠行腹主动脉—下腔静脉分流术。11周后以右心导管法测定肺动脉平均压(pulmonary artery mean pressure，mPAP)。检测右心室／体重(right ventricle／body weight，RV／BW)和右心室／左心室 室间隔(right ventricle／left ventricle plus septum，RV／LV S)比值。并且以光学显微镜和电子显微镜观测肺血管结构的变化。以分光光度法测定血浆硫化氢(hydrogen sulfide，H2S)含量。化学法测定肺组织硫化氢产出率，以原位杂交的方法检测肺动脉胱硫醚—γ—裂解酶(cystuthionine—γ—lyase，CSE)mRNA表达。结果：分流组大鼠mPAP、RV／BW及RV／(LV S)比值明显高于对照组，光镜下肺小血管肌化程度明显增强，肺中、小肌型动脉相对中膜厚度明显增加。电镜下，肺中、小肌型动脉内皮细胞增生、肥厚、肿胀，平滑肌细胞增生、肥厚，并由收缩表型向合成表型转化。分流组大鼠的血浆H2S含量及肺组织CSE活性(肺组织H2S产出率)明显低于对照组，肺动脉mRNA表达明显降低。结论：肺血管结构重建是高肺血流量所致肺动脉高压的重要病理基础，内源性H2S体系——mRNA表达、CSE活性及血浆H2S含量下降可能在其形成中起重要的作用。

Effects of high pulmonary blood flow on pulmonary vascular structure and the gene expression of cystathionine-γ-lyase

OBJECTIVE: To examine the alteration of pathologic structure and endogenous hydrogen sulfide pathway in rats with pulmonary hypertension induced by high pulmonary blood flow. METHODS: Sixteen SD rats were randomly divided into shunting group and control group. An 11-week aortocaval shunting was produced in rats of shunting group, and pulmonary artery mean pressure (mPAP) was evaluated using right cardiac catheterization. The ratios of right ventricular mass to body weight (RV/BW) and right ventricular mass to left ventricular plus septal mass RV/(LV+S)] were also detected. Pulmonary vascular micro- and ultra- structures were examined. Meanwhile the concentration of plasma hydrogen sulfide (H(2)S) was measured by spectrophotography. The gene expression of cystathionine-gamma-lyase (CSE)was detected by in situ hybridization, and the activity of CSE in lung tissues was measured by H(2)S production according to chemical analysis. RESULTS After 11 weeks of aortocaval shunting, pulmonary artery mean pressure was significantly increased. Muscularization of small pulmonary vessels and relative medial thickness of pulmonary arteries were obviously increased in shunting rats compared with controls. Ultrastructure of intrapulmonary arteries changed obviously in shunting rats. Meanwhile, plasma H(2)S concentration was decreased and the activity of CSE (according to H(2)S production) in lung tissues decreased in shunting rats. CSEmRNA expression by pulmonary arteries was significantly suppressed. CONCLUSION: Pulmonary vascular structural remodeling is the important pathologic basis for pulmonary hypertension induced by high pulmonary blood flow. The down-regulation of endogenous H(2)S pathway might play an important role in the development of high pulmonary blood flow induced pulmonary hypertension.