[cis-diamminedichloroplatinum cochlear toxicity]

Twenty-nine guinea pigs were divided into three groups. The first group received distilled water 2 ml/kg ip daily; the second group received DDP 2 mg/kg ip daily; and the third group DDP 4 mg/kg ip daily. ABR hearing threshold was tested before injection. Twenty-four hours after systemic administration, ABR hearing threshold was tested again. The animals were killed and the cochlear specimens were observed under light, scanning and transmission electron microscopes. No abnormality regarding ABR hearing threshold and cochlear morphology was observed in the first group. In the second group, ABR hearing threshold was elevated, inner and outer hair cells, supporting cells, striae vascularis and spiral ganglions were damaged. In the third group, ABR hearing threshold elevated markedly. All above-mentioned cells were severely damaged. The experiment showed that the cochlear damage induced by DDP was dose related. The severest damage was seen in the second turn of the cochlea. The damage to the Deiters' cells was earliest and severest. The outer hair cells were more vulnerable to the damage than the inner hair cells did.