[Effect of intravenous administration of micronomicin on the inner ear of guinea pigs].

The present experiment was made to clarify the effect of intravenous administration of micronomicin (sagamicin, MCR) on the inner ear of guinea pigs (300--350 g). MCR was given to the animals intravenously at dose of 25, 50 mg/kg and 100 mg/kg, respectively for 28 days. Pinna reflex test in frequency range from 20 kHz to 0.5 kHz was performed before, during and after the administration. The temporal bones were removed after intravital perfusion of the inner ears with neutral formation after the end of the administration. Histopathological examination was performed on the serial celloidin sections of the inner ears which had been stained with hematoxylin eosin. The following results were obtained. 1. MCR had a mild corti toxicity, which did not show remarkable dose dependent increase. 2. MCR had more affinity for the vestibular organs than for the organ of corti. The affinity for the vestibular organ increased with increase in dose. 3. MCR showed less increase in corti toxicity in intravenous administration than in intramuscular injection. However, the affinity of MCR for the vestibular organ showed little more increase in the intravenous administration than in the intramuscular injection.