Figure 2. Concentration-effect curve for inhibition of22Na+uptake into synaptosomes by propofol. Synaptosomes were pre-incubated in the presence of various concentrations of propofol, and Na+channel-dependent Na+-uptake was evoked with 60 micro Meter veratridine. Nonspecific uptake in the presence of 1 micro Meter tetrodotoxin was subtracted to yield specific uptake (shown as means +/- SEM; n = 3–6). The corresponding concentrations of free propofol shown in the lower scale were determined by high-pressure liquid chromatography after equilibrium dialysis. *P < 0.05 versus control (no propofol) by analysis of variance followed by Fisher's post hoc test.