Fig. 4.

Model of AChRs and predicted properties of mEPCs during open channel block. A, Model predictions of the effects of a 1 msec application of 0.1, 1, and 10 mm ACh (as indicated). The solid curves are exponential fits of the current decay after application of 0.1 and 10 mm with the indicated time constants. B, Model prediction of the voltage dependency of open channel block evoked by ACh (10 mm applied for 1 msec) at +50 and −50 mV. The solid curves are exponential fits of the current decay at either potential with the indicated time constants. Model prediction of the evolution of the kinetic states during a 1 msec application of 10 mm ACh at +50 (C) and −50 (D) mV. Each trace represents a different state: monoliganded (AC) and diliganded closed states (A₂C), the open channel (A₂O), and the blocked channel (A₃B). E, Prediction of the time course of the mEPC at −50 and +50 mV elicited by a 0.125 msec duration pulse of 10 mm ACh. The mEPCs are scaled to a similar peak. The solid curves are exponential fits of the mEPC decay at either potential with the indicated time constants. The rise times were 0.08 msec at +50 mV and 0.12 msec at −50 mV.