Effects of peptide YY on intestinal blood flow distribution and motility in the dog.

Previous investigators in our laboratory have demonstrated that peptide YY (PYY), a putative gut hormone, exerts a potent emetic effect when administered intravenously to conscious dogs. The current study was carried out to examine the effects of an emetic dose of PYY on cardiovascular status, splanchnic blood flow distribution (estimated using 15 micron microspheres) and small intestinal motility in anesthetized dogs. PYY, infused i.v. at a dose of 25 pmol/kg/min led to a localized significant reduction in small intestinal muscularis externa blood flow both 15 and 30 min after the start of PYY infusion in both jejunum and ileum. This decreased muscularis perfusion was not accompanied by any significant change in whole gut wall blood flow and was explained on the basis of an observed significant redistribution of blood flow away from the muscularis towards the mucosa/submucosa. Similar, although non-significant, effects of PYY on colonic blood flow distribution were also observed. Despite the effects on jejunum and ileum, PYY exerted minimal effects on duodenal blood flow. The decrease in ileal and jejunal muscularis blood flows was accompanied by a significant increase in the amplitude of intestinal contractions in these regions. Frequency of contractions was unaltered however. These results demonstrate that PYY infusion leads to concurrent changes in small intestinal blood flow and motility.