Calcium transport in the endolymphatic space of cochlea and vestibular organ.

Ca++ concentrations and d.c. potential within the endolymphatic space of the cochlear duct and the semicircular canal following acute anoxia or ethacrynic acid intoxication (100 mg/kg i.v.) were measured by means of double-barrelled microelectrodes. Ionic calcium content and d.c. potential were found to change in a roughly biphasic fashion after either intervention. The maximal increase in Ca++ concentration coincided with the decline in the d.c. potential, which after a rapid decline finally reached and maintained negative voltages. This phenomenon was more pronounced in the cochlear part than in the semicircular canal. A model of calcium homeostasis is proposed in an attempt to reconcile the data presented with earlier evidence.