Fig. 4. The pharmacodynamic endpoints of the study. ( A ) Heat pain intensity and unpleasantness scored using a 10-cm visual analogue scale (VAS) ranging from 0 (no pain) to 10 (most intense pain or most unpleasant pain experience). ( B ) Electrical pain threshold and tolerance. ( C ) Drug high scores using a 10-cm VAS. ( D ) Cardiac output. Values are mean ± SEM. The gray bars denote the time of S(+)-ketamine infusion (0–120 min).