ROLES OF HISTAMINE AND DIAMINE OXIDASE IN MUCOSA OF RAT SMALL-INTESTINE AFTER ISCHEMIA-REPERFUSION

To examine the roles of histamine and diamine oxidase in the intestine after ischemia-reperfusion, we measured histamine content, diamine oxidase activity, and ornithine decarboxylase activity in rat intestinal mucosa 6 hr following various periods of ischemia. In addition, mortality rates of rats after various periods of ischemia were observed. The superior mesenteric artery was occluded for 15, 30, or 60 min. Ornithine decarboxylase activity increased in the 15-, 30-, and 60-min ischemic groups compared to the sham-operated control group. In the prolonged ischemic group (60-min ischemia), both histamine concentration and diamine oxidase activity in the mucosa decreased, contributing to an increase in circulating histamine. In the 60-min ischemic group, the mortality rate of rats was 25%, which was significantly larger than the control groups. Pretreatment with aminoguanidine, which suppressed diamine oxidase activity, increased the mortality rate. These results indicate that histamine released from the intestinal mucosa has a harmful effect on rats, and diamine oxidase activity plays an important role when the small intestine is subjected to prolonged period of ischemia.