[The effect of calcium ion on ampullary nerve potential]

The effect of calcium ion (Ca2+) in the endolymphatic and/or perilymphatic space of the posterior semicircular canal (p.s.c.) nerve response was studied. When both endolymph and perilymph contained no Ca2+, no p.s.c. nerve response was observed. When only the endolymph contained Ca2+ and the perilymph was Ca2+ free, again no nerve response was observed. On the other hand, when only the perilymph contained Ca2+, p.s.c. nerve response was evoked. Therefore, Ca2+ in the perilymph was considered to be essential for maintaining the function of the p.s.c. as a mechanoreceptor.