Effect of focal cochlear vascular lesion on endocochlear potential in guinea pigs

The alterations in endocochlear potential(EP) in response to the total cochlear ischemia induced by varied experimental manipulations have been studied. However, whether damage to the focal microvessel in the lateral wall of the cochlea can affect the EP value is still unknown. In current investigations, we adapted a photochemical method to produce focal microvessel injury in the lateral wall of the guinea pig cochlea and examine effects of these insults on EP in the same region. It was found that the small focal microvessel lesion (approximately 0.2mm x 0.3mm) did not induce significant changes in EP value. Furthermore, the relative large microvessel lesion (approximately 0.2mm x 0.3mm) did not induce significant changes in EP value. Furthermore, the relative large microvessel lesion (approximately 0.2mm x 0.8mm) produced only a slight decrease in the EP value with experimental procedures and these changes were not significantly different as compared with those in the control group subjects. The results from this study suggest that after focal microvessels in the lateral wall of the cochlea are injured, some compensation mechanisms may play a role in maintaining the cochlear function.