Effect of intestinal ischemia on diamine oxidase activity in rat intestinal tissue and blood.

This study examines the effect of increasing duration of intestinal ischemia on the mucosal integrity and the release of the enzyme diamine oxidase from the small intestine. Acute ischemia was produced by the occlusion of the superior mesenteric artery, and the subsequent changes in DNA and 125I-albumin content in the lumen were taken as indices of intestinal lesions. Diamine oxidase activity was measured in the intestinal lumen, mucosa, lymph, and serum. Occlusions of the superior mesenteric artery for periods of more than 60 min resulted in significant leakage of 125I-albumin (i.v.) into the lumen. In contrast, luminal DNA content rose significantly after 15 min of ischemia and continued to increase proportionally with the increased duration of the occlusion up to 120 min. Similarly, diamine oxidase activity was augmented in the lumen after 15 min of occlusion and rose sharply as the ischemic period was lengthened up to 60 min, leveling off thereafter. Increases in the diamine oxidase activity were also observed in the intestinal lymph and serum, reaching levels that were 2.6 and 3.6 times that of the control respectively after 60 min of ischemia. These findings suggest that intestinal ischemia reduces the diamine oxidase content in the intestinal mucosa by desquamation of the surface epithelial cells and by releasing the enzyme into the intestinal interstitial fluid, from which at least a portion is transported to the blood via the lymphatics. The early release of diamine oxidase seems to occur before the mucosal barrier is broken.