Mast cell degranulation prior to ischemia decreases ischemia-reperfusion injury in the canine small intestine

Objective: To determine the impact of previous mast cell degranulation on i ntestinal ischemia-reperfusion-induced mucosal damaged. Materials:. The hemodynamic and morphological consequences of complete arte rial occlusion were evaluated in anesthetized dogs. The mast cell degranula tor Cremophor-El (n = 5) and Compound 48/80 (n = 5) were used to investigat e the involvement of gastrointestinal mast cells in ischemia-reperfusion-in duced tissue reactions. Seven dogs subjected to complete segmental arterial occlusion served as controls. Intestinal biopsies taken at the end of 120- min ischemia and after 120 min of reperfusion were evaluated histologically . Methods: The number of mast cells was determined and the degree of mucosal damage was evaluated according to the 5 grade Chiu scale. Mucosal histidine decarboxylase activity was measured in tissue samples and the rate of rele ase of histamine was determined from the venous effluent of the ileal segme nt. Results: In the control group, 120-min reperfusion significantly increased the plasma histamine level, and induced a severs tissue injury. In the comp ound 48/80 and Cremophor-El-pretreated groups, the reduction in the baselin e number of mast cells in the villi was 37% and 53 %, respectively, and the ischemia-reperfusion-induced release of histamine was significantly decrea sed. In these groups, the basal mucosal histidine decarboxylase activity wa s significantly increased and the degree of damage of the intestinal mucosa was significantly reduced. Conclusion: It is proposed that mast cell degranulation prior to ischemia m ay induce a potentially protective mechanism in the small bowel mucosa and decreases ischemia-reperfusion injury in the dog.