ObjectivesTo determine if myocardial injury results from hepatoenteric ischemia-reperfusion. We also proposed to determine if this remote heart injury is mediated by a xanthine oxidase-dependent mechanism.DesignRandomized, controlled animal study.SettingUniversity-based animal research facility.SubjectsThirty-six New Zealand white male rabbits, weighing 1.8 to 3 kg.InterventionsAnesthetized rabbits were randomly assigned to one of four groups (n = 9 per group): a) a sham-operated group; b) a sham-operated group pretreated with sodium tungstate (xanthine oxidase inactivator); c) an aorta occlusion group; and d) an aorta occlusion group pretreated with sodium tungstate. Descending thoracic aorta occlusion was maintained for 40 mins with a 4-Fr Fogarty embolectomy catheter, followed by 2 hrs of reperfusion.Measurements and Main ResultsMyocardial injury, manifested by increased circulating creatine kinase-MB fraction activity, was significantly associated with aortic occlusion and reperfusion (p < .05). Sodium tungstate pretreatment significantly (p < .05) reduced circulating and myocardial xanthine oxidase activity. Xanthine oxidase inactivation by sodium tungstate significantly decreased circulating creatine kinase-MB fraction activity after hepatoenteric ischemia-reperfusion (p < .05). Finally, circulating creatine kinase-MB fraction activity was significantly associated with circulating xanthine oxidase activity (r2=.85; p < .001).ConclusionsWe conclude that remote myocardial injury is caused by hepatoenteric ischemia-reperfusion. The pathoetiology of this myocardial injury involves a xanthine oxidase-dependent mechanism. (Crit Care Med 1997; 25:1044-1050)