Effect of nitric oxide and peroxynitrite on mucociliary transport function of experimental otitis media.

Abstract

To determine the role of nitric oxide (NO) and peroxynitrite on mucociliary activity in experimental otitis media with effusion (OME). Twenty guinea pigs were divided into 1 control and 3 experimental groups; lipopolysaccharide (LPS), N(G)-nitro-L-arginine methyl ester (L-NAME), and uric acid (UA) groups. Ten ears were used in each group. OME was induced by transtympanic injection of LPS in experimental groups. Twenty-four hours after the transtympanic injection, dye transfer time (DTT) was measured and the temporal bone was taken for histopathologic examination. Expression of peroxynitrite was determined by immunohistochemical stain for 3-nitrotyrosine (3-NT). Dye transfer time was significantly delayed in LPS group compared to control group; by contrast it was significantly reduced in L-NAME or UA treated groups (P < 0.01). Histopathologic examination showed reduced inflammation and mucosal thickening in the treatment groups when compared to LPS group. These findings, however, were not statistically significant. Immunoreactivity to 3-NT was intense in LPS group and decreased in the treatment groups (P < 0.05). It is suggested that LPS induced mucociliary dysfunction in the middle ear by NO and peroxynitrite-mediated pathways.