Effects of electrical potentials upon hair-cell function

Abstract

Isolated lateral-line preparations from the African clawed toad Xenopus laevis were mounted in a special chamber permitting recording of neural activity during mechanical cupular displacements and/or application of electric potentials across the receptor. Stimuli of frequencies from 1 to 100 Hz were effective in producing phase-locked modulation of spontaneous neural activity. A sample of six fibers had thresholds for electrical and mechanical stimulation of 0.62 ± 0.032 mV p − p and 11.4 ± 17.8 μm p − p, respectively. Electrical and mechanical input-output curves had similar slopes (0.74 ± 0.12 and 0.82 ± 0.31, respectively). Responses in the two afferent fibers innervating the same stitch were 180° out of phase for mechanical stimuli but in phase for electrical stimuli, demonstrating that electrical stimulation produced negligible mechanical movements. Response activity during mechanical stimulation could be modulated by electric potentials, suggesting that both stimuli act upon the same stage of transduction. These results are consistent with the mechano-electrical hypothesis of hair-cell function. [Supported by grants from the Deafness Research Foundation and USPHS 08193.]