The effect of hypothermia on ischemic injury of the cochlea in gerbils was
studied with particular regard to glutamate efflux in the perilymph. Under
normothermic conditions interruption of the blood supply to the cochlea for
15 min caused a remarkable elevation of the compound action potential (CAP
) threshold, and an increase in perilymphatic glutamate. The CAP threshold
recovered to some extent with reperfusion, but not to preischemic levels. C
AP threshold, under hypothermic conditions and with reperfusion, recovered
promptly to near preischemic levels, while glutamate concentration did not
change. These results, together with electron microscopy studies, suggest t
hat hypothermia prevents hearing loss primarily through reduction of glutam
ate efflux at the synopses between inner hair cells and primary afferent au
ditory neurons. NeuroReport 12: 1983-1987 (C) 2001 Lippincott Williams & Wi
lkins.