Study of auditory hair cells with patch clamp method

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The auditory organ of goldfish (saccule) was excised and individual hair cells were obtained by papain treatment and studied with patch clamp method.1. Transduction currents, i.e. currents responding to bending of the sensory hairs were recorded under whole-cell voltage clamp. Only eight recordings were successful yet. Technical improvements are now going on.2. Membrane potential was recorded under whole-cell current clamp. Two types of responses were observed to the square current injection. One is oscillatory change of membrane potential from 50 to 200 Hz, which was seen in ovoid or short cylindrical cells abundant in the rostral part of the saccular macula. The other is slow depolarization and action potential, which was seen in long slender cells abundant in the caudal part.3. Membrane currents were examined with voltage-clamp method under the presence of blockers and/or different ionic composition of the external solution. Ca current, Ca-activate K current, A-current, and inwardly rectifying K current were identified. In addition, transient inward current, probably Na current, was observed.4. Single channel characteristics of Ca-activated K channels (BK channels) were studied under inside-out mode. Their unitary conductance was 150 to 300 ps and it had selective permeability to K. Time course of the response to square voltage steps, measured with internal Ca concentration o 5 M was very fast as compared with similar channels in the chromaffin cell membrane.