Fig. 6. Mean maximum measured coronary sinus (c.s.) and arterial (art.) blood concentrations of thiopental enantiomers and propofol from site-directed left main coronary arterial infusions over 3 min of rac -, R -, and S -thiopental and propofol to conscious adult sheep. Individual enantiomer concentrations were determined by chiral separation after administration of rac -thiopental. Mean values along with their 95% confidence intervals are shown.