[Effects of increasing perilymph calcium levels on various cochlear potentials].

In the present study, we examined the effects of increasing perilymph calcium (12.20 mmol/L) on guinea pig cochlear functions. The results demonstrated that high calcium perilymphs suppressed the magnitude of compound action potential of auditory nerves (CAP) with a prolongation of N1-peak delay at a constant intensity (90 dB SPL), but not of cochlear microphonics (CM). High calcium perilymph didn't change general endocholear potential (G-EP), while reduced the rapid change of EP at on and off set of 115dB SPL white noise exposure. Furthermore the value of negative potential (N-EP) induced by anoxia was decreased because of high calcium perfusions. Machanisms of these effects were discussed.