Kinetics of Endotoxin and Tumor Necrosis Factor Appearance in Portal and Systemic Circulation After Hemorrhagic Shock in Rats

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Abstract
This study was performed to investigate gut-derived bacterial translocation and the time course of endotoxin (lipopolysaccharide [LPS]) and tumor necrosis factor (TNF) appearance, both in portal and systemic circulation. The significance of intestinal bacteria/endotoxin translocation or TNF formation in the development of systemic sepsis has been disputed. A rat model of hemorrhagic shock (30-35 mm Hg for 90 min) and resuscitation was used. Bacterial translocation was histologically observed in the small intestinal wall 30 minutes after resuscitation. A significant increase in LPS concentrations was found in the portal vein (91.7 +/- 30.6 pg/mL) at 90 minutes, which remained steady until 150 minutes after shock. Lipopolysaccharide increased in the systemic circulation, the levels became significant at 120 minutes, and peaked (66.5 +/- 39.2 pg/mL) 150 minutes after shock. Tumor necrosis factor concentrations were found to be significantly elevated in both portal and systemic circulation (75.6 +/- 22.1 vs. 58.4 +/- 14.1 pg/mL) at 90 minutes post-shock. Although there was no further increase in TNF concentration in the portal blood. TNF peaked (83.5 +/- 17.7 pg/mL) in systemic circulation at 120 minutes and still was markedly increased at 150 minutes post-shock. In addition, higher LPS and TNF concentrations in systemic circulation were found in the nonsurvivors than in the surviving animals at the end of resuscitation. These results suggest that hemorrhagic shock may lead to early bacterial translocation in the intestinal wall and transient access of gut-derived LPS and LPS-induced mediators into the circulation predominantly via the portal circulation.