TABLE 2 

Parameters for activation by propofol obtained by fitting concentration-response curves with predictions from the MWC model

The first column gives the concatemers expressed, whereas the second column gives the number of proposed propofol-binding sites mutated. The column headed L₀ gives the ratio P_closed/P_open for that receptor in the absence of added agonists. Data for L₀ are given as arithmetic mean ± S.E.M. (95% confidence limits; number of observations). The P_{open, const} for wild-type βαγ-βα receptors would give an estimate of L₀ = 8676 ± 1429 (n = 8). In other cases, L₀ was estimated from the effect of picrotoxin on currents in the absence of other drugs. N_P is the number of propofol-binding sites assumed in performing the fits (see Materials and Methods); for these values, it was assumed that the wild-type βαγ-βα receptor has N_Prop = 6. c_P gives the ratio of the affinity of propofol to the open-channel to that for the closed-channel forms of the receptor. K_P gives the affinity of propofol for the closed-channel form of the receptor. The values for c_P and K_P are given as best estimate for the parameter ± estimated S.E. provided by the fitting program (Origin v. 7.5).