Effects of hyperbaric oxygen treatment on 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 90 min. 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 111ln and 51Cr, 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.