Direct Evidence of Nitric Oxide Production in the Guinea Pig Organ of Corti

Abstract
Production of nitric oxide (NO) in the organ of Corti of the guinea pig was investigated using the new fluorescence indicator 4,5-diaminofluorescein diacetate for direct detection of NO. The organ of Corti, lateral wall of the cochlea and isolated outer and inner hair cells were examined to locate NO production sites. The fluorescence intensities were augmented by stimulation with L-arginine or glutamate, and significantly increased after inoculation with lipopolysaccharide. This is the first direct evidence of NO production in the cochlea. NO may play an important role in the physiology of the organ of Corti and may also be involved in hearing disorders.