Hypoxia and endothelin-1 （ET-1） are associated with constriction of pulmonary vasculature both in vivo and in vitro. However

the role of hypoxia and ET-1 in the vascular remodelling during the development of pulmonary hypertension is unclear. This study demonstrated that ET-1（0. 1 nmol/L to 100 nmol/L） increased the [￣3H]thymidine uptake in a dose-dependent manner in cultured bovine pulmonary artery smooth muscle cells（PASMC）. which was enhanced by exposing PASMC to hypoxia （2%O2

93%N2

5%CO2 ）. BQ123

the specific antagonist of endothelin receptor subtype A

eliminated the ET-1 medicated proliferation of PASMC and the cooperative effect of hypoxia. Some dilatory drugs could inhibite the mitogenic effect of ET-1. We also observed that hypoxia significantly increased [￣3H] thymidine uptake in PASMC without ET-1 and BQ123 could inhibite this effect. Radioimmunoassay suggested that there was an autocrine of ET-1 in cultured PASMC which was enhanced by hypoxia significantly.