Effect of ethaverine hydrochloride on cochlear microcirculation

The effect of ethaverine hydrochloride on cochlear microcirculation was observed in short-term experiments on 11 guinea pigs. In these experiments, the endocochlear PO2, endocochlear potential (EP), cochlear microphonic (CM) potential, and blood pressure (BP) were recorded. Endocochlear PO2 was measured polarographically by gold electrodes in the scala media. Ethaverine hydrochloride was administered by intravenous infusion for ten minutes in doses of 2, 5, and 10 mg/kg. These experiments demonstrated that ethaverine hydrochloride in doses of 5 and 10 mg/kg caused significant elevation of endocochlear PO2 for 35 to 90 minutes, even when the BP temporarily declined. At the same time, it was observed that this improvement of cochlear microcirculation coincided with an increase of the CM potential. Decrease of the EP is probably the result of BP decline and a direct action of ethaverine on EP generation.