DEXTROMETHORPHAN ATTENUATES THE EFFECTS OF ISCHEMIA ON RABBIT ELECTRORETINOGRAPHIC OSCILLATORY POTENTIALS

Dextromethorphan has been shown to protect against ischemic tissue dam age. We investigated the effects of dextromethorphan on electroretinog raphic oscillatory potentials in retinal ischemia. Retinal ischemia wa s induced in rabbits by increasing intraocular pressure to 120 mm Hg f or 30, 60 or 90 minutes. Dextromethorphan was intravenously administer ed before ischemia and maintained throughout the whole period of exper iments. Oscillatory potentials were recorded before and during ischemi a as well as 4 hours of recirculation after ischemia. As expected, all oscillatory potentials were decreased after 60 and 90 minutes of isch emia. However, after 30 minutes of ischemia followed by 4 hours of rec irculation, amplitudes of P2 were elevated whereas those of P3 and P4 were decreased with normal P1 amplitudes. Dextromethorphan administrat ion diminished the effects of 30 minutes of ischemia on oscillatory po tentials and partially attenuated the effects of 60 minutes of ischemi a, whereas the effects of 90 minutes of ischemia could not be reversed by dextromethorphan treatment. These results indicate that electroret inographic oscillatory potentials, could be useful indicators to evalu ate retinal function in the ischemic condition and that dextromethorph an can attenuate the effects of relatively short periods of ischemia o n rabbit electroretinographic oscillatory potentials.