Chemiluminescence Study of Pe roxynitrite in Experimental Autoimmune Uveitis

ABSTRACT

The purpose of this study is to evaluate the extent of peroxynitrite generation in the pool of radicals/oxidants from intraocular inflammation using luminol-dependent chemiluminescence(LDCL)method. S-antigen induced uveitis was produced in Lewis rats. The rats were killed at the peak of inflammation, and the retinas and choroids were collected for the LDCL. Sodium bicarbonate was used to confirm the peroxynitrite signal. Superoxide dismutase(SOD), N-nitro-L-arginine methyl ester(LNAME)and aminoguanidine(AG)were tried to evaluate the inhibitory effect of superoxide and nitric oxide. LDCL counts for 6 inflamed and 6 control retina/choroid preparations were 66, 429+/-413 cpm and 13, 941+/-105 cpm, respectively(p<0.01). In the presence of bicarbonate, emission was increased by 125.3+/-6.6%(n=6)and the signal was sustained for 2 hours. SOD, L-NAME and AG suppressed the LDCL by 39.8+/-6.1%(n=3), 20.4+/-4.4%(n=3) and 35.9+/-4.0 %(n=3), These observations suggest that peroxynitrite contributes considerably to the generation of the total pool of reactive species by the cellular infiltrate. The presence of a high level of peroxynitrite, a potent oxidizing and nitrating agent, in inflamed retina may cause irreversible tissue damage to the photoreceptors.