Mechanosensory hair cells release chemical transmitters onto associated afferent dendrites and respond to transmitters released by efferent neurons. Dihydropyridine-sensitive, voltage-gated calcium channels support transmitter release from hair cells and may be expressed preferentially at release sites. Recently, a novel subunit of the nicotinic acetylcholine receptor family, alpha9, was identified and found to be expressed in rat hair cells. It appears to mediate efferent inhibition via associated calcium-activated potassium channels.