Fig. 1. Inhibition of carbachol-induced tracheal smooth muscle (TSM) strips contraction by propofol. The TSM strips were divided into three groups, incubated 30 min with dimethylsulfoxide (control, circles ), 100 μM propofol ( triangles ), and 300 μM propofol ( diamonds ), respectively. Cumulative concentration–response curves for carbachol (10 nM to 1 mM) were obtained. Data are normalized to maximal response induced by 50 mM KCl and expressed as mean ± SD of six separate experiments.