Functional significance of nitric oxide in the inner ear.

Significant advances have been made in our understanding of the functional significance of nitric oxide (NO) in the inner ear. The localization of NO synthase and the nitric oxide production site has now been established by immunohistochemistry and the fluorescent indicator of NO. The functional significance of NO in the inner ear, especially as a neurotransmitter, is becoming increasingly clear. Mounting evidence suggests that excessive NO production may play an essential role in inner ear disorders as well. The production of an inducible type of NO synthase may be closely related to this phenomenon. Based on the mechanisms of inner ear disorders, new pharmacological strategies for preventing and/or treating inner ear disorders have also been suggested.