Mesenteric arterial vasopressin in cats: local and systemic effects

The administration of intraaterial mesenteric vasopressin to induce small intestinal ischemia was evaluated in the cat. Small intestinal blood flow was measured by carbonized microsphere distribution and electromagnetic flowmetry. Injection of 99mTc labeled isotope into the superior mesenteric artery was monitored by gamma camera, and isotope kinetics were evaluated as indicators of small intestinal blood flow. Superior mesenteric arterial and small intestinal mucosal blood flow could maximally be reduced to 15%-20% of control by vasopressin administration. 99mTcO4 mesenteric-cardiac transit time was doubled in all animals when small intestinal mucosal blood flow was reduced to less than one-third of control. However, significant blood flow reductions were induced in other abdominal organs, most importantly in retroperitoneal lymph nodes and adipose tissue. Intraarterial mesenteric vasopressin administration does not induce sufficiently severe and specific intestinal ischemia to provide optimal conditions for selective small intestinal hypoxic radioprotection.