Changes in Lipopolysaccharide Concentrations in Hepatic Portal and Systemic Arterial Plasma During Intestinal Ischemia in Monkeys

The time course of changes in the level of plasma lipopolysaccharides (LPS) in both the hepatic portal and the systemic arterial circulations, together with changes in cardiovascular parameters, was ascertained during a 1 hr occlusion of the superior mesenteric artery (SMA) in six primates. The LPS concentrations before occlusion of the SMA in the hepatic portal and systemic arterial circulation were 0.051 +/- 0.009 and 0.065 +/- 0.011 ng/ml, respectively (NS). At the end of the occlusion period, there was no significant increase in either the hepatic portal or systemic arterial plasma LPS concentrations. Immediately on removal of the occlusion, however, the LPS concentration in the portal plasma increased and peaked at 0.431 +/- 0.124 ng/ml (P less than 0.01) within 17.5 +/- 1.71 min, whereas in the systemic arterial circulation the LPS concentration began to rise but only after a delay of approximately 10 min to peak at 0.287 +/- 0.126 ng/ml (P less than 0.05) within 32.5 +/- 4.23 min of reperfusion. The mean arterial pressure (MAP) declined during the reperfusion period from 98.6 +/- 6.89 to 65.0 +/- 9.5 mm Hg (P less than 0.05). The heart rate showed a small but not significant increase (P greater than 0.2) after about 80 min of reperfusion. These data indicate that the gut is the source of the increased plasma LPS concentration following occlusion of the SMA.