Fig. 1 (A ) The fluorescence enhancement recorded on rapidly mixing nAcChoR-rich membranes with 5 mM acetylcholine and either 1 μM, 5 μM, or 40 μM Dns-C6-Cho (final concentrations). The curve superimposed over each trace is a fit of the data to an exponential equation with a linear component. The rates of the fluorescence enhancement induced by 1 μM, 5 μM, and 40 μM Dns-C6-Cho were 9.4 ± 0.3 s−1, 14.1 ± 0.2 s−1, and 46.9 ± 0.5 s−1, respectively. (B ) The rate of the fluorescence enhancement is plotted as a function of Dns-C6-Cho concentration in the absence of isoflurane (0 mM) and in the presence of 0.5 mM, 1.0 mM, or 1.5 mM isoflurane. The curve is a fit of the data to . (Inset ) The K dof Dns-C6-Cho for the nAcChoR agonist self-inhibitory site (K B) is plotted as a function of isoflurane concentration.