Figure 3. Mechano‐electrical transduction by Snell's waltzer IHCs .

A and B, MET currents recorded at −81 mV (left panels) and +99 mV (right panels) from control +/sv (A, P4) and sv/sv (B, P4) apical‐coil IHCs elicited using 50 ms force‐step stimuli (top panels). At −81 mV, +/sv IHCs had a small transducer current at rest and inhibitory bundle displacements turned this off (grey traces). At +99 mV, the resting MET current was increased. In sv/sv IHCs the resting MET current was absent at both membrane potentials (B). The recordings at −81 and +99 mV are from the same IHCs. Resting MET current in the absence of bundle stimulation is indicated by grey dashed lines. C and D, normalized peak MET current recorded from +/sv (C, P4, n = 3) and sv/sv (D, P4, n = 4) IHCs at the holding potential of −81 mV and during a step to +99 mV as a function of driver voltage. Data were fitted with eqn (1). In +/sv (C) at −81 mV a ₁ = 0.41 V⁻¹, a ₂ = 0.094 V⁻¹, x ₁ and x ₂ = 5.4 V; at +99 mV the parameters were as at −81 mV, except for x ₁ = 1.9 V. In sv/sv (D) at positive driver voltages and at −81 mV a ₁ = 0.34 V⁻¹, a ₂ = 0.20 V⁻¹, x ₁ = 8.2 V, x ₂ = 18.0 V; at +99 mV the parameters were as at −81 mV, except for x ₁ = 7.9 V and x ₂ = 17.1 V. For negative bundle stimulation a _1,2 and x _1,2 were negative, but had the same absolute values as for positive driver voltage. The average saturating MET current in IHCs was: −515 ± 90 pA (+/sv) and −288 ± 35 pA (sv/sv) at −81 mV; +912 ± 161 pA (+/sv) and +457 ± 52 pA (sv/sv) at +99 mV. For negative driver voltages in sv/sv IHCs, the saturating MET current was about 0.23 of that for positive driver voltages.