Vasoactive and metabolic effects of leukotriene C4 and D4 in the intestine.

The effects of intra-arterial administration of leukotrienes (LT) C4 and D4 upon total intestinal and mucosal blood flow, intestinal oxygen consumption and motor activity were measured in anesthetized dogs. Blood flow to a segment of distal ileum was measured with an electromagnetic blood flow meter, and arteriovenous oxygen difference (AVO2) was determined spectrophotometrically. Oxygen consumption was calculated as the product of AVO2 and total blood flow. Intestinal mucosal blood flow was determined by a local H2-gas clearance technique. Motor activity was monitored on the basis of changes in intraluminal pressure. LTC4 and LTD4 induced a dose-related decrease in total intestinal blood flow, mucosal blood flow and in oxygen consumption, and an increase in intestinal motor activity. Both LT produced a redistribution of blood flow into the muscular compartment of the intestinal circulation. The results of these studies indicate that LTC4 and LTD4 are potent vasoconstrictors in the intestinal microcirculation, and that endogenous LT may contribute to the microvascular changes leading to the intestinal damage.