Ikeda K, Kusakari J, Takasaka T, Saito Y. Early effects of acetazolamide on anionic activities of the guinea pig endolymph: evidence for active function of carbonic anhydrase in the cochlea.
Hear Res 1987;
31:211-6. [PMID:
2830214 DOI:
10.1016/0378-5955(87)90189-4]
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Abstract
The effect of acetazolamide (ACZ) on HCO3- and Cl- activities in inner ear fluid was investigated by ion-selective microelectrode methods. The endocochlear potential, at 81.6 +/- 1.5 mV under normal conditions, was reduced by 4.9 +/- 0.9 mV in 30 min following the ACZ injection. The HCO3- concentrations by 11.5 +/- 1.7 mM in 30 min, while the change of Cl- level was not consistent but showed a tendency toward slight increase in average. The calculated PCO2 in endolymph was 39.6 mmHg. ACZ induced a constant elevation of the endolymph PCO2, with an increase in the venous PCO2 during the initial 20 min and thereafter the endolymph PCO2 attained a plateau despite the continuous increase of the venous PCO2. We postulate that the HCO3- secretion into the endolymph is mediated by carbonic anhydrase (CAH) and is decreased by ACZ due to the inhibition of CAH.
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