AIMTo investigate the dynamic expression of hypoxia-inducible factor 1alpha, PHDs and OS-9 in pulmonary arteries of rats with hypoxia-induced pulmonary hypertension.

METHODSSD rats were randomly divided into 5 groups (n = 8) and exposed to hypoxia for 0, 3, 7, 14 or 21 d, respectively. RT-PCR and in situ hybridization were used to determine the expression of mRNA. Immunohistochemistry and Western blot were used to determine the expression of protein.

RESULTSHIF-1alpha protein was poorly positive in control, markedly up-regulated after 3 d and 7 d of hypoxia (P < 0.05, vs group C), and then declined slightly after 14 d and 21 d of hypoxia. HIF-1alpha mRNA increased dramatically after 14 d of hypoxia (P < 0.05, vs group C). PHD1, PHD2 mRNA and protein was positive in group C. PHD2 mRNA and protein were up-regulated after 3 d of hypoxia (P < 0.05, vs group C), reaching its peak after 14 d of hypoxia while PHD1 protein declined after 14 d of hypoxia (P < 0.05, vs group C) without statistic mRNA changing. PHD3 mRNA and protein were detected at low level in control, markedly up-regulated after 3 d of hypoxia (P < 0.05, vs group C), and then PHD3 mRNA kept at high level while PHD3 protein declined after 14 d of hypoxia (P < 0.05, vs 7 d). OS-9 mRNA was positively in control, markedly decreased after 3 d of hypoxia (P < 0.05, vs group C), reaching its lowest lever after 14 d of hypoxia. Linear correlation analysis showed that OS-9 protein was positively correlated with OS-9 mRNA (r = 0.82, P < 0.01) and HIF-1alpha protein (r = 0.57, P < 0.01).

CONCLUSIONHIF-1alpha, PHDs and OS-9 are all involved in the pathogenesis of hypoxic pulmonary hypertension in rats. OS-9 may interact with both HIF-1alpha and PHDs to promote PHD-mediated hydroxylation of HIF-1alpha.