A. Campos et al., GENTAMICIN OTOTOXICITY IN OTOCONIA - QUANTITATIVE ELECTRON-PROBE X-RAY-MICROANALYSIS, Acta oto-laryngologica, 114(1), 1994, pp. 18-23
Chronic gentamicin ototoxicity was evaluated in the otolithic membrane
of adult OF1 mice at the otoconial layer of the saccule and utricle b
y quantitative electron probe X-ray microanalysis of Ca and K. The oto
lithic membranes were plunge-frozen and freeze-dried. The analysis was
carried out with an energy dispersive detector using the peak-to-back
ground ratio method and different inorganic salts of Ca and K as stand
ards to calibrate the microprobe. Ca and K in the otoconia are related
via a linear function in both the saccule and the utricle. This assoc
iation is not maintained after exposure to gentamicin, which suggests
that this aminoglycoside antibiotic interferes with the Ca - K equilib
rium in the otoconia. A dose of 200 mg/kg gentamicin twice a day for 5
days did not affect Ca in the mineral phase of the otoconia, but did
increase K in both saccular (p < 0.05) and utricular (p < 0.01) otocon
ia. These increases in K may reflect a modification in the composition
of the endolymph, resulting from cellular damage at the plasma membra
ne.