Interactions of Nitric Oxide and Antioxidants in Hypoxia-Reoxygenation Injury

ABSTRACT

PURPOSE: An ischemia-reperfusion injury leads to profound functional and structural alterations of vascular smooth muscle cells (VSMC). It is still not clear whether hypoxia- reoxygenation and antioxidants affect the nitric oxide (NO) synthesis of VSMC. This study tried to investigate the effects of antioxidants on NO production, inducible nitric oxide synthase (iNOS) and the expression of NFkappaB p65, during the hypoxia-reoxygenation of VSMC cultures. METHODS: The VSMCs were primarily cultured from rat aortae, and confirmed by immunoreaction with the anti- smooth muscle myosin antibody. The condition of the hypoxia was verified by measuring the PO2 and PCO2 of the culture media. The concentrations of nitrite in the culture media were measured by the Griess reaction. Western blottings for the iNOS and NFkappaB p65 proteins were performed. L-NAME was used as an NOS inhibitor. Vitamins C and E, Glutathione (GSH), lipoic acid and dihydrolipoic acid (DHLA) were used as antioxidants. RESULTS: The iNOS protein was induced in the VSMC by 24 hours of hypoxia, which increased the nitrite in the VSMC culture medium. The reoxygenation profoundly increased the iNOS protein expression and nitrite concentration. The L- NAME, vitamins C and E, GSH, lipoic acid and DHLA decreased the nitrite productions during hypoxia and the hypoxia-reoxygenation, whereas, the expressions of the iNOS and NFkappaB p65 proteins were not influenced. CONCLUSION: We concluded that hypoxia-reoxygenation induced the iNOS protein, and the subsequent production of NO in the VSMC. The antioxidants and the NOS inhibitor decreased the NO production during the hypoxia-reoxygenation, but did not affect the expressions of the iNOS and NFkappaB p65 proteins