Angiotensin II and progesterone effects on laser doppler measures of cochlear blood flow

Abstract

Anesthetized, ovariectomized rats were given bolus injections of angiotensin II (AII) or saline vehicle while Cochlear Blood Flow (CBF) changes were measured using a laser Doppler flowmeter. Experimental animals were pretreated with replacement progesterone and control animals were given oil vehicle injections in place of progesterone. AII increased blood pressure and CBF. Progesterone pretreatment augmented AII-induced pressor responses, while slightly depressing the cochlear blood flow response. These results suggest that AII may be involved in the local, autoregulatory control of CBF, and in possible steroid-related alterations of susceptibility to ototraumas.

Key Words:

• angiotensin II
• steroids
• blood pressure
• autoregulation
• laser Doppler velocimetry
• rats