[Changes of cochlear electrical activities in early experimental hydrolabyrinth].

Changes of endocochlear potential (EP), cochlear microphonic potential (CM) and summating potential (SP) were studied in guinea pig cochlea after four weeks blockade of the endolymphatic sac and duct. The EP, CM and SP were measured with a microelectrode through the spiral ligament of the first turn. EP was decreased by 15%. The minimum CM output produced by tone burst of six frequencies (0.5, 1, 2, 4, 5 and 8 KHz) had reduced by 83.1%, 82.4%, 84.5%, 84.2%, 47.2% and 54.2% respectively, and the maximum CM output had declined by 54.3%, 41%, 43.2%, 21.1%, 26% and 24% separately. The minimum SP output caused by 4, 5 KHz tone burst had declined by 62.4% and 70.5%, and the maximum SP output had decreased by 41.5%, 45.2% in the early experiments. These results indicate that EP, CM and SP all underwent decreases. The extent of CM declination at low frequencies was larger than that at the high frequencies in the early experiments. The mechanisms of influence on EP, CM and SP in early experimental endolymphatic hydrops are discussed.