Cochlear Oxygen Tension: Relation to Blood Flow and Function

Abstract

In the normal animal, administration of 100% oxygen, 8% CO₂ or I.V. epinephrine produced increases in perilymph oxygen tension. This value was highest for pure oxygen. Only CO₂ or I.V. epinephrine increased strial blood flow rate and though similar in degree, perilymph oxygen was greater with CO₂ than with epinephrine. With cessation of respiration the oxygen dissolved in the perilymph is exhausted in about 30 seconds. Surgical occlusion of the vena aqueductus cochleae results in a drop in perilymph oxygen tension to about 30% of normal along with a marked (90%) reduction in strial flow rate, and about a 65% reduction in microphonic output. These low values could be raised, particularly with J.V. epinephrine. The reasons for these findings are discussed.