Cholecystokinin and peptide YY are released by fat in either proximal or distal small intestine in dogs.

We tested the hypothesis that the release of cholecystokinin (CCK) and peptide YY (PYY) may be independent of the region of the small intestine exposed to fat. In five dogs equipped with duodenal and midgut fistulas, the small intestine was compartmentalized so that fat was confined to either the proximal or distal one-half of the gut. Plasma CCK and PYY levels were measured by radioimmunoassay and compared by the square root of the area under the curve (sqrt AUC), representing the plasma peptide concentration over time. CCK was released similarly whether fat was delivered into the proximal (69.9+/-4.7 pM) or distal (71.0+/-5.5 pM) gut, but significantly more CCK (88.9+/-5.6 pM; p<0.05) was released when both the proximal and distal gut were perfused simultaneously with fat. PYY was released similarly whether fat was delivered into the proximal (34.9+/-2.6 pM) or distal (40.0+/-1.2 pM) gut or both (38.6+/-2.2 pM). We conclude that CCK and PYY are released by fat in either the proximal or distal one-half of the small intestine.