tokens: In the presence of high concentrations ( propofol 100 microg mL - 1 , thiopental 50 microg mL - 1 ) marked relaxation was observed ( propofol - 32 % up to - 49 % , P < 0 , 05 ; thiopental - 23 % up to - 67 % , P < 0 . 05 ) .