Hemodynamic and metabolic changes during stimulation of ileal motility

Hemodynamic and metabolic responses of the mesenteric circulation were studied during infusion of agents known to stimulate intestinal motility. Agents were infused intraarterially in graded doses and included acetylcholine, angiotensin II, prostaglandin D2, prostaglandin F2-alpha, methionine-enkephalin, and morphine. Measurements were made of blood flow to the ileal portion of the small intestine, arteriovenous oxygen content difference, fractional distribution of radiolabeled microspheres to the muscularis, and intraluminal pressure. The clearance of 86Rb was determined in some experiments. From these measurements we calculated oxygen consumption, fractional blood flow to the muscularis, permeability and surface area product (PS-product), and the mean motility index. All agents increased mean motility index to varying degrees. At comparable levels of increased mean motility index with each drug, there were variable degrees of increase or decrease or no change in the other parameters between drugs. Mesenteric hemodynamic and metabolic responses to these dissimilar stimuli of motor activity reflected mainly the vasoactive properties of each agent. This suggests that increased motor activity has little influence on the mesenteric circulation.