Role of xanthine-oxidase system in mucosal injury after intestinal preservation and transplantation.

THE XANTHINE-OXIDASE (XO) system has been considered to be involved in warm ischemia-reperfusion injury of the small intestinal mucosa. 1 Briefly, during warm ischemia in the small intestine. xanthine dehydrogenase (XD) is converted to XO, which produces superoxide radicals in the presence of its" substrate (hypoxanthine and xanthine) and oxygen.2 Meanwhile, adenosine triphosphate (ATP) is degraded and its degradation product. hypoxanthine. accumulates in the mucosal tissue.z Upon reperfusion (rewanning and reoxygenation), the mucosal tissue is damaged by superoxide radicals produced by converted XO, oxygen, and accumulated hypoxanthine.3 In order to examine whether the XO system is the cause of cold ischemia-reperfusion injury, mucosal XD. XO hypoxanthine. and maltase (MAL) (as an index of mucosal injury) were measured in an autotransplantation model of 24-hour preserved canine intestine.