Fig. 2. Dose-response curve of propofol in concentrations ranging from 1 to 50 μg/ml, at a calcium concentration of 1.36 mm (n = 7, closed circles). At concentrations of 5 μg/ml and higher, propofol induced a significant depression of force development (**P < 0.01; ***P < 0.001). The open circles represent the dose-response curve of propofol at an external calcium concentration of 0.5 mm.