Figure 1. (A) Equilibrium fluorescence intensity of Dns-C⁶-Chol under conditions of energy transfer from nAcChoR tryptophan residues in the presence of nonanesthetics. The excitation wavelength was 290 nm, and emission was recorded above 560 nm. The predicted EC⁵⁰s for 1,2-dichlorohexafluorocyclobutane and and 2,3-dichlorooctafluorobutane are 16 micro Meter and 4.5 micro Meter, respectively. Data are the means (+/-SD) of at least three determinations. (B) Stern-Volmer plots for nAcChoR-rich membrane intrinsic fluorescence quenching by halothane. Data are the means (+/-SD) of at least three determinations.