Effects Of The Novel Endothelin Receptor Antagonists On The Proliferation Of Rat Pulmonary Arterial Smooth Muscle Cells

Objective:To study the effects of the novel endothelin receptor antagonists on the proliferative behavior of cultured rat pulmonary arterial smooth muscle cells(PASMCs)Methods:Primary culture of rat PASMCs was prepared by the method of tissue block anchorage.PASMCs were divided into five groups:control,model, model+BQ-485,model+ETP-508,model+GF-063.The PASMCs proliferation was determined by MTT(492nm)assay and cell cycle was measured by flow cytometry.The endothelin level in the supernatant was detected by radioimmunoassay.Results:1.MTT assay:At 24h,OD value did not exert significant effect on the each group.At 48h hypoxia group significantly increased,the value was 0.386±0.017.The group of hypoxia+BQ-485,hypoxia+ETP-508,hypoxia+ ETP-508 significantly decreased respectively.The values of different groups were 0.343±0.021,0.333±0.022,0.329±0.026.Each group compared with hypoxia group(P＜0.01).At 72h,hypoxia group was increased,but less than 48h(P＜0.05).In model of ET-1,the value of group were 0.346±0.0142,0.248±0.048,0.240±0.036,0.254±0.045 in ET-1 group,ET-1+BQ-485 group,ET-1+ ETP-508group,ET-1+GF-063 group respectively,each group compared with control group(P＜0.05).2.Celluar cycle assay:The percentage of cell and DNA synthesis of model was increased significantly at G₂ and S periods(P＜0.01～0.05).Compared with model,the percentage of cell of model+BQ-485,model+ ETP-508,model+ GF-063 was decreased at G₂ and S periods(P＜0.05),the percentage of cell was increased at G₁(P＜0.05). 3.ET-1 assay:The supernatant of ET-1 in hypoxia was increased(P＜0.01). The supernatant of ET-1 in hypoxia+BQ-485(10^-7mol/L)group,hypoxia+ ETP-508(10^-9mol/L)group,hypoxia+ GF-063(10^-9mol/L)group were degraded respectively(P＜0.01).The value were 152.11±7.47pg/ml,109.61±7.62pg/ml,117.34±3.58pg/ml,124.45±11.70pg/ml.The level of ET-1 in ET-1 group, BQ-485(10^-7mol/L)treated group,ETP-508(10^-9mol/L)treated group and GF-063(10^-9mol/L)treated group were 175.97±1.96pg/ml,166.58±3.68 pg/ml,165.35±4.26 pg/ml,161.81±2.97 pg/ml,respectively.(each group compared with control group,P＜0.05).Conclusions:ETP-508 and GF-063 were the novel endothelin receptor antagonists which inhibit the proliferation of PASMCs induced by hypoxia and ET-1.ETP-508 and GF-063 may significantly decrease the supernatant of ET-1 level than BQ-485.ETP-508 and GF-063 would become the drug to treat pulmonary artery hypertension.