Study Of Pulmonary Artery Smooth Muscle Cell Proliferation,Apoptosis And Expression Of Survivin Induced By Monocrotaline In Rats

OBJECTIVETo study the relationship of cell proliferation and apoptosis in pulmonary arterial smooth muscle cell and the expression of apoptosis inhibitor -survivin during the remodeling process of pulmonary vascular structure , we establish the model of pulmonary hypertension (PH) induced by monocrotaline (MCT) in rats . This study can provide experimental evidence for improving the clinical symptoms in patients with PH .METHODS40 rats were divided into control group and MCT group randomly. MCT group was the model of pulmonary hypertension induced by MCT, while the control group was injected by normal saline . All rats were killed at 2 weeks and 4 weeks . In order to reflect the morphological changes of pulmonary vascular conditions , the mean pulmonary artery pressure (mPAP) was detected by right heart catheter , the right ventricular hypertrophy index (RVHI) was calculated , the small artery's structure was detected by HE dyeing , the diameter and wall thickness of small artery was measured and the ratio of wall thickness and vascular diameter (WT%) was calculated ; to observe the cell multiplication of pulmonary artery smooth muscle (PASMCs) , the expression of proliferating cell nuclear antigen (PCNA) was detected by immunohistochemical staining ; the apoptosis of pulmonary artery smooth muscle was detected by situ DNA nick end labeling (TUNEL) , the proliferation index (PI) , apoptotic index (AI) and PI/AI was also calculated . The expression of survivin was detected by immunohistochemical staining and Western Blot. RESULTS1. The mPAP and WT% in MCT group is higher than the control ( at 2 weeks P< 0.05,at 4 weeks P<0.001) ; in MCT group all index of 4 weeks is higher than 2 weeks ( P< 0.01). At 4 weeks, the RVHI in MCT group is higher than the control, while at 2 weeks, there is no difference. From the HE stained preparation we can find the thickening of muscular layer and endomembrane in pulmonary artery in MCT-2 weeks group and MCT-4 weeks group , while in control group , the endomembrane is smooth, the endothelial cells is continuous , the vessel wall is thin and thickness uniform .2. The PI , AI and PI/AI in MCT group is higher than the control group (P<0.01) . The PI and PI/AI in MCT-4 weeks group is higher than the MCT-2 weeks group (P<0.01) , the AI in MCT-4 weeks group is also higher than the MCT-2 weeks group (P < 0.05) , PI/AI is positively correlation to WT% (r=0.881,P<0.001).3. There is no survivin expression in the control group, while in MCT group the expression is ascending, the Immunohistochemistry and Western blot in MCT-4 weeks group is higher than MCT-2 weeks group (P < 0.01). The expression of survivin is positively correlation to WT% and PI/AI(r=0.78, P<0.001;r=0.948,P<0.001).CONCLUSIONS1. During the formation of HP , the multiplication and apoptosis of the smooth muscle of pulmonary artery is increased, while the ratio of multiplication and apoptosis is also increased , this disequilibrium is the cause of reconstitute of pneumoangiogram .2. The survivin is higher expressed in the smooth muscle of pulmonary artery, and the reconstitution of the pneumoangiogram is followed the expression of survivin, survivin can inhibit the apoptosis of smooth muscle cell and promote the multiplication.