Objective To investigate the dynamic expression of small ubiquitin-related modifiers-1 ( SUMO-1) in lung tissue in different phases of rat model of hypoxic pulmonary hypertension( HPH) .Methods Forty Wistar rats were randomly divided into 5 groups, and exposed to normoxia or to normobaric intermittent hypoxia for 3, 7, 14 or 21 days, respectively. Mean pulmonary arterial pressure( mPAP) , right ventricle hypertrophy index ( RVHI) , and the ratio of the vessel wall area to the total area( WA% ) weremeasured. RT-PCR and in situ hybridization were used to determine the mRNA expression of SUMO-1.Immunohistochemistry and Western blot were used to determine the protein expression of SUMO-1. Results The hypoxic rats developed pulmonary vascular remodeling in pulmonary arterioles after 7 days of hypoxia,with WA% and mPAP significantly higher than those in the normal control. Pulmonary vascular remodeling aggravated with much higherWA% and mPAP afer 14 days of hypoxia, and reached the peak afer 21 days of hypoxia. SUMO-1 mRNA and protein expression markedly increased after 3 days of hypoxia, and reached peak after 14 days. After 21 days of hypoxia, SUMO-1 mRNA expression weakened but still higher than that in the normal control ( P lt; 0. 05) , and SUMO-1 protein expression remained stable. SUMO-1 mRNA and protein expression were positively correlated with mPAP, WA% and RVHI( all P lt; 0. 01) . Conclusion SUMO-1 is transcriptionally induced in lung tissue under chronic hypoxia, and thus involves in the pathogenesis of HPH.
