Table 1.

Stiffness recovery by bullfrog hair cells

Hair cell no.	Initial stiffness, μN·m−1	Stiffness after EDTA exposure, μN·m−1	Stiffness after recovery, μN·m−1	Endolymph Ca2+ concentration, μM
1*	490 ± 26	211 ± 13	311 ± 14	25
2*	339 ± 17	171 ± 14	211 ± 10	25
3*	501 ± 24	217 ± 12	322 ± 15	250
4	365 ± 19	205 ± 11	320 ± 26	250
5	1,039 ± 85	246 ± 12	860 ± 53	250
6	478 ± 17	292 ± 10	415 ± 16	250
7	452 ± 13	269 ± 11	302 ± 14	250

Each stiffness was estimated by measuring the flexion of a flexible glass fiber attached at the hair bundle’s tip during sinusoidal stimulation. Asterisks indicate bundles subjected to step displacements; the remainder were displaced with ramps. Values are reported as means ± SDs for 21 determinations. For the entire sample, the stiffness decreased significantly after exposure with respect to the initial value (P < 0.007). After the negative displacements, the stiffness recovered significantly with respect to the exposed value (P < 0.04). If we disregard the cell (number 5) with an exceptionally high stiffness, the corresponding values show still greater significance (P = 0.0001 and P < 0.002, respectively).