Fig. 6. Effect of pretreatment with 1.0 minimum alveolar concentration isoflurane (ISO) or sevoflurane (SEV) on reductions in left ventricular developed pressure (LVDP) caused by exogenous superoxide produced by xanthine oxidase and purine. Presented are maximal changes, which occurred after 10 min exposure. Values are expressed as mean ± SD. *P < 0.05 versus  baseline value. †P < 0.05 versus  control group (no pretreatment).