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. 2008 Jan 4;94(7):2639–2653. doi: 10.1529/biophysj.107.123257

FIGURE 8.

FIGURE 8

Simulated MT currents and hair-bundle mechanics on two different models. (A) Channel release model (b2): applied step force (F), bundle tip displacement (X), and the probability of MT channel opening (pO). The X and pO responses are averages of 10 simulations. Intracellular calcium at the fast-adaptation site with the MT channel open was 100 μM. (B) Calcium-induced reduction in the gating spring (rK): same simulations as in A. rK = 0.8 represents a maximal reduction in stiffness of 80%. (C) pO-X relationships of the channel on the “channel release” model (b2, solid circles) and on the “reduction in gating spring stiffness” model (rK, crosses). Results fitted with a single Boltzmann. (D) Force-displacement (F-X) relationships of the bundle for the two models. In addition, two passive conditions with no channel activity were also modeled. To simulate a hair cell treated with DHS, all the MT channels were blocked. To simulate a BAPTA-treated hair cell, the tip links were removed. KHB at X = 0 is 3.6 mN·m−1 (control; b2), 3.9 mN·m−1 (control; rk), 5.3 mN·m−1 (DHS), and 1.8 mN·m−1 (BAPTA). (E) pO-X relationships on the channel release model at the peak of the response (solid circles, inst) and after 1 ms (open circles, ss). (F) F-X relationships on the channel release model at the peak of the response (solid circles, inst) and after 1 ms (open circles, ss). Note that the instantaneous plot is close to that without channel activity in the presence of the blocker DHS.