Acute effects of noradrenalin related vasoactive agents on the ototoxicity of aspirin: an experimental study in the guinea pig.

Aspirin is known to be ototoxic when administered at high doses. Its mode of action is unknown but an alteration of the vascular function has been suspected. To further document this hypothesis, acute effects of some vasoactive agents on the ototoxicity of aspirin were tested in experiments on the guinea pig using sensori-neural electrophysiological responses and morphometry of the vessels of the stria and the spiral lamina. Electrophysiological measures showed no modification of sensory responses but neural responses revealed clear changes after administration of noradrenalin related agents, limited modifications after a drug acting partly as a serotonin antagonist, and no change after a dopaminergic agent. Morphometric studies showed no modification of the strial but some effect on the spiral vessels. The results are compatible with the hypothesis of a vascular involvement in the ototoxicity of aspirin and they point toward an interaction with the noradrenergic sympathetic cochlear system in the spiral lamina.