RESUMO
These experiments were designed to investigate the effect of noise, sleep, and gentamicin on the cochlear microphonic (CM) of the guinea pigs. Are the changes observed due to intrinsic cochlear phenomena or to efferent system actions? To answer this question, noise exposure together with efferent system blockade by gentamicin administration was performed. In the normal (non-treated) animal, noise exposure decreased both variability and amplitude of the tone evoked CM in about the first 10 min while the physiological modulation of slow wave sleep increasing the CM is not present. Following administration of gentamicin, noise no longer affect the CM in about the first 10 min, although it produces amplitude and variability increments. The influence of slow wave sleep on the CM is not altered. Thus, gentamicin does not block the CM sleep/wakefulness related shifts. The data were discussed in terms of the influence of gentamicin on the olivo-cochlear bundle. It was hypothesized that the effects of noise on the CM is a result of both peripheral and central influences.
Assuntos
Antibacterianos/efeitos adversos , Potenciais Microfônicos da Cóclea/fisiologia , Gentamicinas/efeitos adversos , Ruído/efeitos adversos , Sono/fisiologia , Vigília/fisiologia , Animais , Antibacterianos/administração & dosagem , Potenciais Microfônicos da Cóclea/efeitos dos fármacos , Vias Eferentes/efeitos dos fármacos , Vias Eferentes/fisiologia , Gentamicinas/administração & dosagem , CobaiasRESUMO
The effects of furosemide and xipamide on guinea pig cochlear potentials were studied under acute conditions. Auditory nerve action potentials (AP) and cochlear microphonics (CM) were depressed by both diuretics in a dose-related manner. Furosemide was more effective on AP than on CM. In contrast, the xipamide-induced reductions of AP and CM were similar. Our results suggest that the depressive effects of furosemide or xipamide may be related to a direct action on cochlear mechanisms.