“…Numerous studies of oxygen metabolism in the cochlea [Hsu, 1992;Koide et al, 1964Koide et al, , 1966Mizukoshi and Daly, 1967;Saito et al, 1995;Spoendlin and Balogh, 1963;Vosteen, 1960;Yang and Han, 1991;Yang et al, 1990] have shown that succinate dehydrogenase (SDH) and other mitochondrial respiratory enzymes, such as cytochrome oxidase, are active in inner hair cells (IHCs), OHCs, Deiters' cells, other supporting cells, spiral ligament, stria vascularis (SV) and spiral ganglion neurons. Acoustic overstimulation [Vosteen, 1960] or administration of ototoxic drugs [Kaku et al, 1973;Koide et al, 1966;Mizukoshi and Daly, 1967] decreases oxygen consumption and reduces SDH activity levels in hair cells (HCs) and/or nerve fibers prior to HC loss.…”