Background:Current researches have shown that pulmonary vascular remodeling is one of the most important mechanisms for CTEPH, which share the homoioplastic pathological characteristics with IPAH. It has been reported that the defected Kv channels induced membrane depolarization and [Ca2+]cyt inflow increasing in PASMCs proliferation for pulmonary vascular remodeling, which is one of the most consistent stimulus for IPAH patients. However, despite intensive clinical features of CTEPH has been reported, the cellularand molecular determinants of pulmonary vascular remodeling are still in mystery.Objective:To observe the changes of Kv channels in PASMCs of CTEPH patients.Methods:andmaterials-Using enzymatic method to isolated the PASMC like cells fromendarterectomized tissues of CTEPH patients undergoing PTE and normal lung tissues ofbronchogenic carcinoma or bullae patients, and then SM-a-actin, MHC and S100A4 were used toidentify the them. Patch clamp and confocal microscopy techniques were used to measure Em, K+channels currents and [Caz2+] in two groups. The mRNA expressions of Kv1.3, Kv1.5, Kv2.1 andKv3.4 were detected by Real-time PCR. The cell proliferation was tracked by MTT method in 9days after seeding.Results 1) Human PASMC like cells from the two groups were successfully isolated and culturedthat was confirmed by SM-a-actin, MHC or S100A4 staining. 2) The amplitude of Kv channelscurrents in CTEPH group (n=14) were significantly diminished than in Normal ones (n=13, P<0.01).4-AP could partly inhibited these currents just in Normal group but not in CTEPH group. 3) ThemRNA expressions of Kv1.3, Kv1.5, Kv2.1 and Kv3.4 channels in PASMC like cells of CTEPH group were lower conspicuously compared with Normal group (n=4, P<0.01). 4) Em in PASMC likecells of CTEPH group is more depolarized than that in Normal group (P<0.01). 5) [Caz+]; ofPASMC like cells in CTEPH patients is apparently higher than Normal group (P<0.001), whichcould inhibited by Nifedipine (P<0.01). 6) The cells proliferation markedly increasing in CTEPHgroups contrast with Nomal group (P<0.05).Conclusions:The declined function and expressions of Kv channels might be the major reason forPASMC like cells proliferation and vascular remodeling in CTEPH patients.