Effects of BAPTA on hair-bundle stiffness of an OHC. (A) Control motion of the fixed end of the fiber (Δx1, upper), the end attached to the hair bundle (Δx2, middle), and MT current (lower). (B) Same measurements after a 2-s puff of a BAPTA-containing saline that abolished the MT current. (C) MT current plotted against instantaneous displacement (upper) and force plotted against steady-state displacement relationships (lower). The force-displacement plots are given before (solid circles, KHB = 2.5 mN·m−1) and after BAPTA application (crosses, KHB = 1.1 mN·m−1). P8 rat, IMAX = 490 pA. (D) Comparison of the two displacements of similar size shows the extra secondary component before BAPTA treatment. Stiffness of fiber, 1.9 mN·m−1.