The Effect of Carbonic Anhydrase Inhibitor on the Otoconia and the Otoconial Membrane -A Scanning Electronmicroscopic Study-

Acetazolamide, in a daily dose of 100 mg/kg;was injected intraperitoneally for 21 days in 5 guinea pigs and 5 mice. Changes on the otoconia and the otoconial membrane were investigated by SEM. In most of the animals the number of otoconia in both the utricle and the saccule was decreased. In some animals with a marked reduction in otoconia, the entire mesh-work structure of the macular membrane was even visualized. Sensory cilia were sometimes seen through the otoconial membrane. Otoconia were more markedly decreased in the saccule than in the utricle. The remaining otoconia showed some changes:giant, dumbell-shaped or spongy surfaced otoconia. Acetazolamide seems to inhibit the crystalization of the calcium bicarbonate contained in the otoconial precursor. Carbonic anhydrase may contribute to the formation and maintenance of the otocoinal membrane.