GASTRIC INTRAMUCOSAL PH AND MULTIPLE ORGAN INJURY - IMPACT OF ISCHEMIA-REPERFUSION AND XANTHINE-OXIDASE

Objectives: To determine if gastric intramucosal pH is affected by hep atoenteric ischemia reperfusion. We additionally proposed to determine if changes in gastric mucosal hydrogen ion concentration are associat ed with liver and lung injury following hepatoenteric ischemia-reperfu sion. Finally, we hypothesized that gastric intramucosal pH is influen ced by xanthine oxidase, an oxidant-generating enzyme released after h epatoenteric ischemia-reperfusion. Design: Randomized, controlled, ani mal study. Setting: University based animal research facility. Subject s: Thirty-six New Zealand white male rabbits (2 to 3 kg). Intervention s: Anesthetized rabbits were randomly assigned to one of four groups ( n = 9 per group): a) sham-operated group; b) sham-operated group pretr eated with sodium tungstate (xanthine oxidase inactivator); c) aorta o cclusion group; and d) aorta occlusion group pretreated with sodium tu ngstate, Descending thoracic aorta occlusion was maintained for 40 min s with a 4-Fr Fogarty embolectomy catheter, followed by 2 hrs of reper fusion. Measurements and Main Results: Gastric tonometry was per forme d after completion of the surgical preparation (30-min equilibration) and at 30, 60, 90, and 120 mins of reperfusion, Plasma alanine aminotr ansferase activity was determined at 120 mins of reperfusion to assess hepatic injury, Bronchoalveolar lavage of the right lung was performe d after 120 mins of reperfusion, and the protein content was determine d as a measure of pulmonary alveolar-capillary membrane compromise, De scending thoracic aorta occlusion resulted in a significant decrease i n gastric intramucosal pH as compared with sham operated rabbits (p<.0 01). The change in gastric mucosal hydrogen ion concentration was sign ificantly associated with plasma alanine aminotransferase activity (r( 2) =.48, p<.01) and bronchoalveolar protein content (r(2) =.51, p <.01 ), Xanthine oxidase inactivation significantly improved gastric intram ucosal PR after aortic occlusion and reperfusion (p<.001), with a conc omitant attenuation of the release of plasma alanine aminotransferase (p <.05) and accumulation of bronchoalveolar protein (p<.05) during re perfusion. Conclusions: Gastric intramucosal pH was significantly decr eased after hepatoenteric ischemia-reperfusion. Furthermore, an increa se in gastric intramucosal hydrogen ion concentration was associated w ith a concomitant increase in tissue injury, a presumed harbinger of m ultiple organ failure, Gastric intramucosal pH values improved during reperfusion after xanthine oxidase inactivation, concomitant with atte nuation of hepatic and pulmonary injury. Gastric tonometry is an impor tant clinical tool that can provide critical insight into the pathogen esis of multiple organ injury after hepatoenteric ischemia reperfusion . Gastric tonometry may aid in the rapid assessment of pharmacologic i nterventions designed to attenuate multiple organ injury in similar cl inical settings (e.g., trauma, shock, major vascular surgery).