Effect of Artificial Endolymph Injection into the Cochlear Duct on Endocochlear Potential

Abstract

Acute endolymphatic hydrops was produced by the injection of artificial endolymph into the cochlear duct of guinea pigs. The endocochlear potential (EP) of the basal turn was measured during endolymph volume increase and anoxia. The ears were grouped into untreated, 0.5, 1.0, and 2.0, μl volume increase. The +EP increased only slightly as the volume increased. Anoxic changes in the EP occurred more slowly in acute hydropic ears than in untreated ears. In contrast, the lowest -EPs were -41.2mV in untreated ears, 31.0mV in 0.5μl ears, -23.3mV in 1.0μl ears, and -22.2mV in 2.0μl ears. There were significant differences in the lowest -EP between the untreated group and the acute volume increased groups (p<0.01 ; t-test).The results of this study show that the causes of changes in +EP and -EP are different.