A model for the study of nonocclusive intestinal ischaemia.

The effects of mesenteric ischaemia have till now been studied in the laboratory by two methods: mechanical occlusion of the proximal superior mesenteric artery, which is followed by functionally reduced bloodflow in the terminal branches; and reduction in cardiac output (leading to shock) brought about by induced atrial fibrillation of cardiac tamponade, this leading to reflex mesenteric vasoconstriction. A new method is described in which noradrenaline is infused into the mesenteric circulation of anaesthetized dogs to produce vasoconstriction. The immediate effects are emptying of the normally full vessels, spasm of the midgut smooth muscle, and pallor with deepening cyanosis. After 60 min subserosal ecchymoses, and haemorrhages into the mucosa and submucosa appear, with sero-sanguinious transudate into the bowel lumen and, eventually, mucosal necrosis. The model described here may facilitate further study of the regulatory mechanisms underlying "nonocclusive" mesenteric ischaemia.