The effects of frusemide, bumetanide and piretanide on the quinea pig cochlea and auditory nerve.

Frusemide, bumetanide and piretanide were introduced into scala tympani of the guinea pig cochlea by perfusion. The short-term effects of these drugs on the cochlear microphonic, the compound action potential and on the activity of single auditory nerve fibres were studied. the compound action potential was more sensitive to the action of the above compounds than was the cochlear microphonic. Single auditory nerve fibres showed a marked increase in threshold and generally a fall in spontaneous firing rate. A deterioration in in tuning was observed which in some cases, was not invariably accompanied by a rise in threshold. Histological examination revealed oedematous changes in stria vascularis and in supporting cells following cochlea perfusion with the above compounds.