Aim: 

Hypoxia-inducible factor-1 (HIF-1) is a transcriptional activator with physiological relevance during exercise. HIF-1 regulates genes involved in increasing oxygen delivery, facilitating ATP production in the absence of oxygen, and even, promoting the regeneration of muscle tissue. This study is aimed to examine the interaction between HIF-1 and one of its target genes, the inducible nitric oxide synthase (iNOS), after an acute bout of eccentric exercise and the contribution of pharmacological inhibition by the antioxidant pyrrolidine dithiocarbamate (PDTC).

Methods: 

Twenty four male Wistar rats were allocated to three experimental groups: rested control group, acutely exercised group after an intermittent protocol downhill, and acutely exercised group treated with PDTC (two doses of 100 mg/kg). In samples of deep vastus lateralis muscle, electrophoretic mobility shift assay (EMSA) of HIF-1, chromatin immunoprecipitation assays (ChIP) and analysis of gene expression (RT-PCR and Western Blot) of iNOS were performed.

Results: 

Acute exercise induced a marked activation of HIF-1 that was significantly blocked in rats treated with PDTC. The binding of HIF-1 to the iNOS promoter was undetectable by ChIP in control rats, whereas it was evident after an acute bout of exercise. This increased binding was partially diminished with the administration of PDTC. The significant increase in iNOS mRNA and protein levels observed in acutely exercised rats was also inhibited by treatment with PDTC.

Conclusion: 

This study is the first to demonstrate the interaction of HIF-1 with the muscle iNOS gene after an acute bout of eccentric exercise. Prevention of HIF-1 activation and iNOS gene targeting by administration of PDTC seems to indicate a protective effect of the antioxidant on exercise-induced injury.