Measurement of Perilymphatic Oxygen Tension for Evaluation of Vasoactive Agents

Abstract

Perilymphatic oxygen tension in cats was measured following one intravenous administration of vasoactive agents. Intravenous infusion and one drop of the agent on the vessels in the internal acoustic meatus were also administered. Vasoactive agents used were papaverine hydrochloride, dihydroergotamine methanesulfate, histamine phosphate, nicotinic acid, eupaverine, naftidrofuryl, low molecular weight dextran, adrenaline and noradrenaline.
Significant discordance of the perilymphatic oxygen tension was detected with the cochlear blood flow as reported by Suga et al³⁾. Namely increase in cochlear blood flow does not always indicate the same trend as seen in the perilymphatic oxygen tension. Dilatation of the vessels in the internal acoustic meatus does elevate the perilymphatic oxygen tension, however effective oxygen supply to the inner ear is also dependent upon other factors influencing the systemic blood circulation. We conclude that vasoactive agents for inner ear diseases should be evaluated not by cochlear blood flow, but by the perilymphatic oxygen tension.