Guinea Pig Cochlear Blood Flow under Definite Sound Exposure-Hydrogen Clearance Measurement

Abstract

Blood flow measurements were carried out on 18 coloured guinea pigs (8 animals served as control group) before and during definite sound exposure (12 kHz, 110 dB SPL). The exposure time amounted to 60 min. The anaesthesia was carried out according to the following schedule: a mixture consisting of 70 mg α-chloralose/kg b.w. and 400 mg urethane/kg b.w. was injected intraperitoneally. The relaxation was performed by means of i.p. application of 3 mg Tricuran/kg b.w./h. The hydrogen clearance measurements (HCM) were carried out under artificial respiration with control of arterial pH, endexpiratory CO₂ content, as well as blood pressure and body temperature. After a duration of noise exposure of 30–45 min the cochlear blood flow reached an average level of 80% of the initial point. This level remained mainly unchanged until the end of noise exposure (60 min). Our HMC’s confirm Laser Doppler flowmetry findings.

Cochlear Blood Flow Measurement in Patients with Me´nie`re's Disease and Other Inner Ear Disorders

“…In Ménière's disease various degrees of atrophy of the stria vascularis have been observed in conjunction with extensive endolymphati c hydrops (1). A reduction in cochlear blood ow (CoBF) has been suggested to occur in presbyacusis (2) and in noise-induced hearing loss (3). Sudden deafness may also be caused by altered circulation in the inner ear (4,5).…”