Figure 9.

Somatic contractions measured in rat isolated hair cells. A, Membrane currents (middle traces) and changes in length (Δx, bottom traces) in an outer hair cell in response to a series of depolarizing and hyperpolarizing voltage steps. Intracellular solution contained CsCl. B, Same measurements made 5 min after starting perfusion with 0.2 mm DHS, indicating no effect of the antibiotic on maximum movements or modest effect on the currents. C, Dependence of length change, Δx, on membrane potential for the responses in A (filled circles) and B (open circles). Also shown is the variation of length change with membrane potential in another outer hair cell recorded with an intracellular solution containing Cs₂SO₄ and gluconate as the principal external anion. Smooth curves are fits to the following: Δx/Δx_max = (1 + exp ((V_0.5 − V)/V_ϵ))⁻¹, where V_0.5 and V_ϵ were −43 and 27 mV, respectively, for control chloride, −26 and 29 mV in the presence of DHS, and +133 and 48 mV for sulfate. Outer hair cells isolated from a P11 rat (DHS experiment) and a P13 rat (Cs₂SO₄ experiment).