Changes of Type I Collagen in Pulmonary Arteries of Rats with Monocrotaline-Induced Pulmonary Hypertension

Objective To examine the expression of typeⅠcollagen in pulmonary arteries of rats with monocrotaline(MCT)-induced pulmonary hypertension(PH) and explore the mechanism of pulmonary vascular structural remodeling.Methods Twelve male Wistar rats were randomly divided into 2 groups: the MCT group(n=6) and the control group(n=6),which received a single intraperitoneal injection of MCT solution(60 mg·kg-1,the first day) or 9 g·L-1saline,respectively.After 3 weeks,mean of pulmonary artery pressure(mPAP),the value of right ventricle/(left ventricle plus septum)[RV/(LV+S)] and body weight were measured.Lung sections(HE stained) were observed under lightmicroscope for changes of the pulmonary arteries.The protein expression of typeⅠcollagen in pulmonary arteries was detected by immunohistochemical technique.Results Three weeks after MCT injection,compared with control group,mPAP and RV/(LV+S) increased significantly in MCT group[mPAP:(10.60±2.06) mmHg(1 mmHg=0.133 kPa) vs(32.40±3.24) mmHg,P0.01;RV/(LV+S):(0.28±0.04) vs(0.47±0.10),P0.01];The body weight in rats of MCT group was significantly lower [(291.4±11.6) g vs(252.7±6.8) g,P0.01].Damages in vascular endothelial cells of pulmonary arteries of rats received MCT injection were observed and showed hyperplasy of smooth muscle.Lumens of arteries were narrowed,even occluded,and the normal structure of artery wall was remodeled.The protein expression of typeⅠcollagen in medium-sized pulmonary arteries and arterioles were both significantly higher in rats of MCT group than those of control group(medium-sized artery:0.23±0.01 vs 0.27±0.02,P0.01;small-sized artery:0.24±0.01 vs 0.30±0.02,P0.01).Conclusions Accumulation of pulmonary artery collagen,one of the pathologic features of pulmonary vascular remodeling,contributed a great deal to the formation of pulmonary vascular structural remodeling in rats with MCT-induced PH.