Influence of Hypotension on Cochlear Blood Flow in Polycythemic Condition

Abstract

We examined the influence of hypotension by infusion of acebutolol hydrochloride (AH), a cardioselective β-receptor antagonist, on cochlear blood flow in guinea pigs with various hematocrit values. AH infusion lowered the mean blood pressure to almost the same degree in all animals, regardless of the hematocrit level. the degree of the concomitant decrease of CBF varied with the hematocrit, being greater in animals with a higher hematocrit. in those with the highest hematocrit CBF did not return to the initial level. From these values we calculated the 0₂ transport capacity after AH infusion and found it to be lower than in animals without AH infusion. the difference was greater at higher hematocrits. These findings suggest that the microcirculation of the inner ear is responsive to transient decreases of perfusion pressure at high hematocrits.

Key Words:

• cardioselective β-receptor antagonist
• hemorheology
• O₂ transport capacity