Figure 2. Maximal isometric developed force and maximal shortening amplitude with increasing concentrations of racemic ketamine (light shaded square, n = 12), S(+)-ketamine (black square, n = 12), and R(-)-ketamine (open square, n = 11). Dark shaded square = 3 [micro sign]M esmolol added to increasing concentrations of racemic ketamine (n = 4). Significant differences of the comparison between increasing concentrations of either the isomers or the racemat with the initial control are shown (*P < 0.05).