Figure 9.

The time course of recovery from desensitization. The points are from Dilger and Liu (1992) and were obtained using a two-pulse protocol. The first pulse of 100 μM ACh desensitized virtually all AChR in the patch. After a delay, the second pulse was applied to test the fraction of AChR that had recovered from desensitization. The abscissa is the interpulse interval (note the logarithmic scale) and the ordinate is the fractional recovery. The solid line is for the optimal values of Model IV (allosteric model). The initial step of recovery, the dissociation of agonist from desensitized AChR, occurs with a rate constant of ∼23 s⁻¹ (per transmitter binding site), and the final, agonist-independent step of recovery occurs with a rate constant of ∼4 s⁻¹.