Effect of Calcium Deficiency on Cochlear Potentials

Abstract

Calcium deficiency in the cochlea was induced by perfusing the perilymphatic space with calcium-deficient solutions in guinea pigs. The effect of calcium lack in the perilymph on the cochlear potentials and on the activity of crossed olivocochlear bundle was studied. Removal of calcium caused a reversible depression of action potential and a slight decrease of cochlear microphonics. The endocochlear potential did not show depression. These changes were enhanced by addition of disodium ethylenediamine-tetraacetate. Calcium lack in scala tympani affected cochlear potentials more severely than that in the scala vestibuli. The removal of calcium from scala tympani blocked the slow negative potential in the scala media produced by crossed olivocochlear bundle stimulation. Calcium deficiency in scala tympani failed in augmentation of cochlear microphonics, suppression of action potential, and increase of positive summating potential produced by olivocochlear bundle stimulation. The role of calcium in the transducer action and the synaptic transmission of crossed olivocochlear bundle was discussed.