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 ox idase activity, and ornithine decarboxylase activity in rat intestinal mucosa 6 hr following various periods of ischemia. In addition, morta lity rates of rats after various periods of ischemia were observed. Th e superior mesenteric artery was occluded for 15, 30, or 60 min. Ornit hine decarboxylase activity increased in the 15-, 30-, and 60-min isch emic groups compared to the sham-operated control group. In the prolon ged 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 m ortality rate of rats was 25%, which was significantly larger than the control groups. Pretreatment with aminoguanidine, which suppressed di amine oxidase activity, increased the mortality rate. These results in dicate that histamine released from the intestinal mucosa has a harmfu l effect on rats, and diamine oxidase activity plays an important role when the small intestine is subjected to prolonged period of ischemia .