EFFECT OF ENDOPLASMIC CA2-ATPASE INHIBITORS ON COCHLEAR POTENTIALS INTHE GUINEA-PIG()

The effect of endoplasmic Ca2+-ATPase inhibitors on cochlear potential s was examined iii the guinea-pig. Perilymphatic perfusion with thapsi gargin (10(-6) M) produced a significant decrease in tile amplitudes o f cochlear microphonics, negative summating potential and compound act ion potential, and a significant prolongation of N-1 latency with Ilo change iu the endocochlear potential. These changes were all dose depe ndent. Another endoplasmic Ca2+-ATPase inhibitor, cyclopiazonic acid ( 10(-5) M), produced the same effects as thapsigargin on cochlear poten tials. These results suggest that endoplasmic Ca2+-ATPase inhibitors m ay have inhibitory functions on cochlear potentials.