Observations on cochlear blood flow using the laser doppler method in guinea pigs

Abstract

Cochlear blood flow of the guinea pig was measured using the laser Doppler method. Blood pressure and respiratory rhythm were also recorded simultaneously. The reliability of this method was substantiated by comparing it with the hydrogen clearance method using rabbit auricles. The blood flow of the auricle was altered artificially by clipping these vessels and then simultaneously measuring the blood flow by the two methods (Doppler and hydrogen clearance). The data obtained by these two methods were closely correlated. Norepinephrine induced both an elevation of blood pressure and an increase in cochlear blood flow in the guinea pig. Phentolamine, on the other hand, induced a fall in blood pressure and a slight decrease in cochlear blood flow. In addition, phentolamine completely blocked the effects of norepinephrine on blood pressure and cochlear blood flow. In this experiment, the responses of blood pressure and cochlear blood flow induced by norepinephrine and phentolamine were dose-related.

Key Words:

• hydrogen clearance method
• blood pressure
• dose-related response
• basal turn of the cochlea