Acetylcholine modulated potassium channel in the hair cell of the toadfish saccule.

Sensory transduction in the acoustic-lateralis system is modulated by an efferent synapse on the sensory hair cells and afferent fibers. Acetylcholine has been implicated as a neuro-transmitter at this synapse. This work addresses the ionic mechanism of action of acetylcholine on the hair cell of the toadfish saccule using path clamp methods and single channel recording. Acetylcholine and oxotremorine, a muscarinic agonist, were found to increase the open time and opening rate of a high conductance K+ channel in the basolateral walls of the hair cell. This effect is not dependent on the presence of Ca2+ in the extracellular media. The involvement of an intracellular mediator is implicated since bath applied agonist opens K+ channels isolated under the recording pipette.