Transduction and adaptation after BAPTA treatment

I, transduction current*S, slipping rate constantC, climbing rateExtent of adaptation§Z, gating force
Control45 ± 22 pA136 ± 50 s−113 ± 4 μm·s−10.73 ± 0.0833 ± 4 fN
 (1 hr)(n=8)(n = 5)(n = 5)(n = 5)(n = 5)
BAPTA0 pA (n = 7)
 (1 hr)
Control38 ± 10 pA117 ± 12 s−114 ± 2 μm·s−10.45 ± 0.0237 ± 9 fN
 (24 hr)(n = 8)(n = 5)(n = 5)(n = 4)(n = 5)
BAPTA30 ± 17 pA 22 ± 3 s−1 7 ± 2 μm·s−10.41 ± 0.1316 ± 1 fN
 (24 hr)(n = 9)(n = 5)(n = 5)(n = 5)(n = 6)
  • In response to subsaturating, 400-nm displacement. 

  • Adaptation rate constant for positive displacements; this is the maximum slope of displacement–adaptation rate curves (21). These rate constants have not been adjusted for the geometrical gain of the bundle, γ. Because stimulus amplitude affects adaptation rate, rate constants are reported (21). 

  • Maximum adaptation rate for negative displacements >500 nm; because saturating negative displacements remove any external force applied to the adaptation motor, motors climb at a constant rate (21). These rates have not been adjusted for the geometrical gain of the bundle, γ. 

  • Determined from displacement–extent curves (22); extent is distance of movement of the adaptation motor in response to a 150-msec stimulus, expressed as a fraction of stimulus amplitude. 

  • Determined from two-state Boltzmann fit to displacement–open probability curve (15); the gating force (Z) indicates the displacement sensitivity of the trandsuction apparatus.