ADRENERGIC CONTROL OF COCHLEAR BLOOD FLOW

The adrenergic control of cochlear blood flow was studied with intravenous administrations of adrenergic, adrenergic blocking and antiadrenergic agents in guinea pigs anesthetized with a barbiturate. Cochlear blood flow changes were recorded from the basal tum utilizing an electrical impedance plethysmograph. Simultaneous recordings of cochlear potential, carotid artery pressure and ECG were made. Agents which are both a and β receptor stimulants increased cochlear blood flow with a rise in systemic blood pressure. The a receptor stimulants produced a transient decrease and a subsequent increase in cochlear blood flow. This increase appears to be a secondary change produced by a rise in systemic blood pressure. The β receptor stimulants appear to produce weak vasodilation in the cochlea, although cochlear blood flow readily decreased with a fall in systemic blood pressure with large doses of these drugs. The a-adrenergic blocking agents increased cochlear blood flow while the β-adrenergic blocking agent decreased it. The antiadrenergic agent caused an initial increase and a subsequent decrease in cochlear blood flow. The cochlear vessels appear to be weakly controlled by the adrenergic nervous system, and this control is easily overcome by changes in systemic blood pressure. There was no apparent change in cochlear potential attributable to these autonomic nervous system agents. © 1969, SAGE Publications. All rights reserved.