The relationships among reactive oxygen species, hypoxia-inducible factor 1alpha and cell proliferation in rat pulmonary arterial smooth muscle cells under hypoxia.

The objectives of this paper were to observe the changes of reactive oxygen species (ROS) in rat pulmonary arterial smooth muscle cells (PASMCs) under hypoxic condition and to test if hypoxia-induced proliferation of PASMCs was mediated by ROS. PASMCs were divided into three groups: normal group, hypoxia group and hypoxia + Mn-TBAP (a ROS scavenger) group. The level of ROS was determined by a laser scanning confocal microscope. The expression of hypoxia-inducible factor 1alpha (HIF-1alpha) mRNA was detected by semi-quantitative reverse transcription PCR (RT-PCR). HIF-1alpha protein was detected using immunohistochemical staining, and the proliferation of PASMCs was examined by MTT colorimetric assay. The results were as follows: (1) The level of ROS in hypoxia group was significantly increased as compared with that in the normal group (P<0.05). The level of ROS in hypoxia + Mn-TBAP group was significantly decreased as compared with that in hypoxia group (P<0.05), but was increased as compared with that in the normal group (P<0.05). (2) The expressions of HIF-1alpha mRNA and protein in hypoxia group and hypoxia + Mn-TBAP group were increased as compared with those in the normal group (P<0.05), and these changes were more significant in hypoxia group than those in hypoxia + Mn-TBAP group. (3) The proliferation of PASMCs in hypoxia group was more obvious than that in the normal group and hypoxia + Mn-TBAP group (P<0.05), and the proliferation of PASMCs in hypoxia + Mn-TBAP group was increased more significantly than that in the normal group (P<0.05). The results indicate that ROS is significantly increased in rat PASMCs under hypoxia, and that ROS affects the expression of HIF-1alpha and the proliferation of PASMCs under hypoxia. Therefore, ROS may play an important role in the pathogenesis of pulmonary hypertension and hypoxic signal transductions.