Figure 10. Membrane tension dependence of the Cl⁻ current.

A, sigmoidal I–V curves were derived from trace-averaged currents recorded with Cl⁻-free Tris-Hepes patch pipette in the presence of Tris-Hepes (circles) and 80 Cl (triangles) extracellular solutions before (filled symbols) and after (open symbols) turgor pressure increases in the initially cylindrical OHC (V_hold= 0 mV, step from +60 to −100 mV). Currents are substantially increased and pressure sensitive in Cl⁻-containing solution. Inset: C–V functions, corresponding to the treatments in A, reflect a significant increase in membrane displacement charge and are shifted in the hyperpolarizing direction in Cl⁻-containing solution. The additional charge increase and C_m shift in the pressurized state (▿) is due to increased Cl⁻ flux, because in Cl⁻-free solutions (^), as well as in Cl⁻-saturated solutions (Kakehata & Santos-Sacchi, 1995), the C_m functions are shifted to depolarizing potentials with positive pressure. B, non-linear charge (Q_max), determined from C–V function fits (n = 3) does not increase in initially collapsed cells in Cl⁻-containing extracellular solution (140 Cl) until Cl⁻ flux is restored by cell re-inflation.