Abstract
In order to investigate the cause of the changes of the cochlear potentials in vitamin D deficiency rats, namely prolongation of N1 latency, depression of CM amplitude and elevation of CM threshold, Ca2+ concentration in perilymph was measured by Ca2+ selective microelectrode. The result was that Ca2+ concentration in perilymph showed 3.3×10-4M (n=4) in vitamin D deficiency rats and 7.4×10-4M (n=4) in controls and its ratio to serum Ca2+ concentration exhibited 63% and 57%, respectively.
The cause of the decrease in perilymphatic Ca2+ concentration in vitamin D deficiency rats was thought to be due to the secondary effect of the decrease in serum Cas2+ concentration. But the gradient of Ca2+ concentration between perilymph and serum was maintained to be normal in vitamin D deficiency rats.
It is postulated that this secondary decrease of Ca2+ concentration in perilymph and possibly in endolymph had an effect on the acoustic transduction and the synaptic transmission, by which the alternations of N1 and CM were induced.
