Effects of propofol and thiopental on the toxicity of amyloid β-protein (Aβ) assembled in the presence of GM1 liposomes. Aβ solution (50 µm) was incubated at 37°C for 24h in the absence or presence of GM1 liposomes with or without 20 µm propofol, 100 µm thiopental or 0.1% dimethyl sulfoxide (DMSO) in a cell-free system. Toxicity is indicated by the amount of lactate dehydrogenase (LDH) released from primary neurons (3 days in vitro) treated at 37°C for 48h with culture medium and incubation mixtures (1:1) containing Aβ at a final concentration of 25 µm. Each value indicates the percentage level of LDH released after treatment with the incubation mixtures, relative to the concentration of LDH released after treatment with Triton X-100. Each column represents the average of six values ± SD. *P < 0.001 (one-way ANOVA combined with Scheffe test).