THE EMERGENCE OF FREE-RADICALS AFTER ACOUSTIC TRAUMA AND STRIAL BLOOD-FLOW

The effect of acoustic trauma on cochlear strial circulation was inves tigated immunohistologically in the guinea pig. Kanamycin was used as a tracer of blood flow. Moreover, histochemical examinations were made to reveal the emergence of free radicals in the cochlea following aco ustic trauma. At 5 min (5 min after intense sound exposure 120-125 dB SPL, 3 h) the blood flow in the stria vascularis was greatly diminishe d. At 2 h the strial blood Row started to recirculate and at 6 h it ap peared to have returned to normal. Superoxide anion radicals (O-2(-)) emerged along the luminal membrane of the marginal cells of the stria vascularis at 5 min. O-2(-) disappeared at 30 min, but reappeared at 2 h. The cause of its emergence at 5 min was obscure. However, the stra nge phenemenon that O-2(-) emerged again at 2 h seemed ascribable to t he re-circulation of strial blood flow after sound exposure.