Localisation et cinétiques de deux antibiotiques aminoglycosidiques à potentialité toxique différente. La gentamicine et l'amikacine dans les cellules sensorielles de l'oreille interne

Abstract
In order to determine the relation between uptake of aminoglycoside antibiotic (AA) molecules by sensory cells of the inner ear and their ototoxicity, we studied the kinetics in cochlear and in vestibular cells of two AAs : gentamicin (GM) (both cochleo- and vestibulo-toxic) and amikacin (AK) (mainly cochleo-toxic). Guinea pigs were treated during six days with one daily injection of GM (60 mg/kg/day) or AK (450 mg/kg/day). AAs were detected in isolated cells using immunocytochemical technique with scanning laser confocal microscopy. Results demonstrate a rapid uptake and a very slow clearance of both AAs from cochlear and vestibular hair cells. Particularly GM and AK are detected in type I and type II hair cells of the utricles and cristae ampullaris. The presence of these two molecules with different toxic potentialities towards the cochlea or the vestibule in cochlear as well as in vestibular hair cells indicate that the selective toxicity of aminoglycosides cannot be explained solely on the basis of particular uptake and accumulation in the different sensorineural receptors.