Physiological effects of extracellular nucleotides in the inner ear.

1. Electrochemical homeostasis, sound transduction and auditory neurotransmission in the cochlea are influenced by extracellular purines and pyrimidines. 2. Evidence that ATP and related nucleotides influence inner ear function arises from a considerable number of cellular, molecular and physiological studies in vitro and in vivo. 3. With a full understanding of these processes, which include ionotropic (P2X receptor) and metabotropic (P2Y receptor) signal transduction pathways, signal termination involving ecto-nucleotidases and recycling via nucleoside transporters, exciting possibilities emerge for treating hearing disorders, such as Meniere's disease, tinnitus and sensorineural deafness.