ALTERATIONS IN MUCOSAL MORPHOLOGY AND PERMEABILITY, BUT NO BACTERIAL OR ENDOTOXIN TRANSLOCATION TAKES PLACE AFTER INTESTINAL ISCHEMIA AND EARLY REPERFUSION IN PIGS

Ischemia and reperfusion of the gut may be an important etiological factor in the development of multiple organ failure. We have used a hemorrhagic and a superior mesenteric artery (SMA) occlusion shock model in pigs to estimate the effect of ischemia and reperfusion on intestinal morphology, mucosal permeability, and the occurrence of bacterial or endotoxin translocation. Mucosal ulceration and necrosis were found in the SMA shock model, while the morphological changes were less pronounced in the hemorrhagic shock model. Scanning electron microscopy showed shrinkage of the villi and plugging of the colonic crypts in both shock models. Enterocyte cell kinetics was investigated using 5-bromo-2'-deoksyuridine (BrdU) incorporation and immunovisualization by anti-BrdU antibodies. Cell renewal was almost completely lost from the jejunum to the rectum in both shock models. Intramucosal pH was measured using a tonometer placed in the terminal ileum. Segments of intestinal mucosa were mounted in Ussing chambers, and permeability was measured using radioloabeled probe molecules of differing molecular weights, Augmented molecular flux of inulin (M(r) 5.000) and mannitol (M(r) 182) and loss of short circuit current (I-sc) and transepithelial potential difference (PD) were found in mucosae from both shock models. Endotoxin was demonstrated in the ascitic fluid in both shock models; 9.5 (2.7-14.3) (median and 95% confidence interval) EU/mL in the SMA occlusion model and 16.0 (4.9-29.4) EU/mL in the hemorrhagic shock model), but the levels were not significantly higher than in the control model 6.5 (4.3-34.0) EU/mL. In agreement with this, no pathogenic bacteria or endotoxin could be detected in the systemic circulation, portal blood, lymph, or in homogenates of mesenterial lymph nodes, liver, or lung. These findings suggest that there is no translocation of bacteria and endotoxin to the systemic circulation during intestinal ischemia and early reperfusion even though the mucosa morphology is highly aberrated and its permeability increased.