[The effects of hypoxia on nitric oxide synthase activity and mRNA expression of pulmonary artery endothelial cells in pigs].

The aim of the study is to investigate whether hypoxia might affect nitric oxide synthase (NOS) activity or mRNA expression of cultured pulmonary artery endothelial cells in pigs by means of NADPH-diaphorase cytochemical stain and DNA-RNA dot blot hybridization respectively. The NOS activity and mRNA expression were highly present in normoxic group as well as 6 and 24 hours serum-free control groups, but significantly lowered in 6 and 24 hours hypoxic groups. The mRNA expression of NOS gene was almost absent in 48 hours hypoxic cells. The results indicate that hypoxia can attenuate the activity and mRNA expression of NOS in cultured pulmonary artery endothelial cells, which may lay an important role in modulating acute hypoxic pulmonary vasocontriction and chronic hypoxic pulmonary arterial hypertension.