TABLE VII.

Simulation Parameters for Schemes B1x and F3x

	Scheme B1x	Scheme F3x
kD+1	30	30
kD−1	400	400
kD+2	18	18
kD−2	33	33
kT+1	84	96
kT−1	144	655
kT+2	—	61
kT−2	—	497

Data were simulated according to Schemes B1x and F3x using the method of Clay and DeFelice (1983). k_D+1 and k_D+2 are rate constants governing the entry of the receptor into the fast and medium duration desensitized states and k_D−1 and k_D−2 are the rate constants for exit from those states. k_{T+ 1} and k_T+2 are the association rate constants and k_T−1 and k_T−2 are the dissociation rate constants for tacrine binding at two sites within the open channel. Values of rate constants governing desensitization were derived by iterative simulation of data according to Scheme Ax, varying the rate constants until the closed time histogram replicated our experimental data obtained at 100 mM ACh (−70 mV values). Values of k_T+1, k_T+2, k_T−1, and k_T−2 are from the maximum likelihood fits of Schemes B1 and F3 to our experimental data (−70 mV).