Effects of arterial occlusion on endocochlear DC potential and cochlear blood flow in guinea pigs

The present study was undertaken to investigate the role of collateral arteries in cochlear circulation by examining the effect of occlusion of branches of the basilar artery on endocochlear DC potential (EP) and cochlear blood flow (CBF). EP and CBF were measured at the basal turn of the cochlea during microclamp occlusion of the basilar artery, its branches and the posterior inferior cerebellar artery (PICA). CBF was measured with a laser Doppler flowmeter. Systemic blood pressure (SBP) increased at occlusion of the basilar artery, but was not influenced by any occlusion of its branches. Changes of EP and CBF at occlusion of the basilar artery were classified into two types: recovery type and non-recovery type. Thirty-five guinea pigs were classified into three groups according to the number of branches of the basilar artery: Group A with one branch in 10 animals (29%), Group B with two branches in 20 animals (57%), and group C with three branches in 5 animals (14%). From the results obtained at successive occlusions of branches of the basilar artery and PICA, it is clear that the anterior inferior cerebellar artery (AICA) supplies blood to the cochlea more or less in all animals, although the reduction of the blood volume by its occlusion is not enough to decrease EP in some animals. When vascular dysfunction occurs in AICA of such animals, other branches of the basilar artery and/or PICA will play an important role to maintain cochlear circulation.