Cochleotoxic effects of spermine and kanamycin

Aminoglycosides are organic bases that contain multiple amino groups. The ototoxic potential of these amine groups was studied using spermine, which is a polyamine with four amine groups (two amino and two imino). Twenty-four pigmented guinea pigs were studied. One-tenth milliliter of different concentrations of kanamycin A sulfate or spermine were given intratympanically. The temporal bones were removed 4 days after the injections, and the cochleas were examined using the scanning electron microscope. The damage to the hair cells was recorded in cytocochleograms. The results show that spermine is cochleotoxic when given intratympanically. Dosage of 50 mumol for kanamycin A sulfate and 5 mumol for spermine caused total damage of the outer hair cells in all ears. Lower dosage of kanamycin A sulfate (20 mumol) and spermine (1 mumol) did not cause any histologically discernible changes.