Aim: To study the protective role of melatonin (MT) in peroxynitrite-induced injury in cultured aortic smooth muscular cells (ASMC).
Methods: Peroxynitrite was synthesized chemically with a quenched flow reaction. Cells were exposed to peroxynitrite 500 micromol/L for 1 h in the absence or presence of various concentrations of MT 100, 300, and 500 micromol/L. Nitrotyrosine (NT), a specific "footprint"of peroxynitrite formation, was detected by immunohistochemical technique. The DNA damage was assayed by TUNEL technique. The levels of MDA in the medium and cell viability were measured.
Results: Incubation of ASMC with peroxynitrite 500 micromol/L for 1 h elicited the increase in the extent of immunostaining for NT, the rate of the TUNEL-positive cell, the content of MDA in the medium, and the number of dead cell. Pretreatment of ASMC with MT 100-500 micromol/L decreased these peroxynitrite-induced changes in a concentration-dependent manner.
Conclusion: MT attenuated the injury induced by peroxynitrite in ASMC.