Effects of different mode of hypoxia on activator protein-1 in cardiac muscle of rats

Abstract

Objective To investigate the effects of different mode of hypoxia on activator protein-1 (AP-1) in cardiac muscle of rats, which is a transcription factor susceptive to oxidation-reduction. We use the expression of c-fos mRNA to indirectly represents the activation of AP-1. Methods Ninety-six male Wistar rats were divided randomly into the three groups: intermittent hypoxia (IH) group, sustained hypoxia (CH) group and the normal oxygen control (SC group. At the second, fourth, sixth, and eighth weeks, eight rats under each group were sacrificed to collect cardiac muscles of right ventricle.Real-time PCR assay was used to detect the expression of c-fos mRNA. Results After 6 weeks of hypoxic exposure, the expression of c-fos mRNA was found to be significantly different in all three groups ( F =13. 455, P =0. 000). The expression of c-fos mRNA in IH group was significantly higher than the SC and CH group ( F values were 104. 285 and 45. 286, P values were 0. 000 and 0. 037). Continued exposure to 8 weeks, there was significant differences among groups ( F =11. 279, P =0. 000). The expression of cfos mRNA in IH and CH group were significantly higher than the SC group ( F values were 112 and 75. 375, P values were 0. 001 and 0. 018). We did not observe the significant differences between the IH and CH groups. Conclusions The increased expression of c-fos mRNA can be caused by intermittent hypoxia and sustained hypoxia. Which intermittent hypoxia may lead to more strongly AP-1 activation than the continuous hypoxia, which induced severe inflammatory reaction. Key words: Intermittent hypoxia; Obstructive sleep apnea; Activator protein-1