Significance of reperfusion injury after venous strangulation obstruction of equine jejunum.

Fifteen horses under halothane anesthesia were assigned randomly to three groups of 5 horses each as follows. In group 1, the distal 50% of the small intestine was measured through a ventral midline celiotomy and replaced in the abdomen so that these horses could serve as sham-operated controls. In group 2, the same segment of small intestine was subjected to venous strangulation obstruction (VSO) for 180 min. In group 3, the same segment of small intestine was subjected to VSO for 90 minutes, followed by 90 minutes of reperfusion. Biopsies of small intestine were taken from all horses to assess mucosal morphologic injury by light microscopy, to measure tissue levels of malondialdehyde as an indicator of lipid peroxidation, and to measure tissue myeloperoxidase activity as a measure of neutrophil accumulation. VSO for 90 min in horse jejunum increased lipid peroxidation and neutrophil influx to levels that remained constant over the following 90 min, regardless of whether VSO was maintained or was interrupted to allow reperfusion of the tissue. Reperfusion induced a similar mucosal lesion as continued VSO for the same time. From these results, it would appear that VSO causes more severe mucosal damage and inflammation than the subsequent reperfusion period, in contrast to the classical paradigm of reperfusion injury in small intestine.