Endothelin-induced long-lasting mesenteric vasoconstriction: a hypothetical mechanism of non-occlusive intestinal...

The in vivo mesenteric vascular effect of the novel, endothelium-derived endogenous polypeptide, endothelin-1 (ET-1) was examined in experiments performed on pentobarbital-anesthetized dogs. Blood supply to a segment of the small bowel was measured simultaneously with an electromagnetic flow probe and computer-assisted thermography which senses flow-dependent infrared irradiation. It was found that close mesenteric arterial injections of ET-1 produced long-lasting flow decreases of considerable magnitude: the single dose of 1 nmol reduced blood flow by nearly 90 percent, and even the minimal single amount of 1 pmol produced statistically significant vasoconstriction. The thermographic analysis proved the homogenous character of these reactions. Unlike vascular responses elicited by most of the known vasoconstrictive agents, the ET-1-induced spastic effects were maintained without a continuous exposure (drug infusion). All features that characterize the spastic ET-1 action qualify the peptide for a hypothetical candidate of mediating the nonocclusive mesenteric ischemic syndrome.