Effects of hyperbaric oxygen treatment an neutrophil activation and pulmonary sequestration in intestinal ischemia-reperfusion in rats

Treatment with hyperbaric oxygen (HBO) has shown promising results in some models of ischemia, the major effect being a reduction in the local ischemic damage. The present study investigated the effects of HBO treatment on neutrophil activation and leukosequestration during reperfusion following intestinal ischemia in a rat model. The superior mesenteric artery was clamped for 2 h and subsequently reperfused for 90min. One group of male Sprague-Dawley rats (n = 9) was given HBO and another group (n = 9) served as controls. Prior to ischemia, leukocytes and erythrocytes were separated, radiolabelled with (111)ln and Cr-51, respectively, and reinfused. Leukocyte transit factor, the ratio between the mean passage time of leukocytes and erythrocytes was used to quantitate leukosequestration and the fraction of circulating, spontaneously nitroblue tetrazolium (NBT)-reducing neutrophils was used to measure the degree of neutrophil preactivation. HBO treatment reduced the level of leukocyte pooling significantly, especially in the lungs but also, to a minor degree, in the systemic vascular bed. The percentage of NBT-positive cells increased in all animals after reperfusion, but the increase was significantly reduced by HBO treatment. In conclusion, HBO treatment reduces leukosequestration and neutrophil preactivation following intestinal ischemia-reperfusion.