EFFECTS OF DEXTROMETHORPHAN ON ISCHEMIA-INDUCED ELECTRORETINOGRAM CHANGES IN RABBIT

The present study was undertaken to determine whether dextromethorphan (DM), a potent N-methyl-D-aspartate antagonist, could attenuate the e ffects of ischemia on rabbit ERG. Retinal ischemia was induced by incr easing intraocular pressure to 120 mm Hg for 30, 60, or 90 min. DM was intravenously administered before ischemia and maintained throughout the entire experimental period. ERGs were recorded prior to, during, a nd after ischemia. The results indicate that the b-wave hyperresponses and the delays in implicit times induced by 30 min. ischemia were sup pressed by the administration of DM. Similar findings were obtained wh en ischemia lasted for 60 min, except that DM did not improve delayed implicit times, suggesting that cellular injury is still present. ERG changes resulting from 90 min ischemia were not reversed by DM treatme nt. Effects of DM treatment on a-wave were less prominent. Together, o ur results further support that DM can to some extent alleviate ischem ic injury in the rabbit retina.