Time course for entry of intestinally infused lipids into blood of rats.

The early time course of the absorption of duodenally infused 14C-labeled Intralipid into either the hepatic portal circulation or systemic circulation was measured. Plasma radioactivity did not increase significantly at either site until 30 min after the intestinal infusion began and was maximal between 60 and 120 min. In studies on the effects of intestinal lipid infusions on sham feeding in rats we find significant suppressions of sham feeding after only 10 min. Thus the time course for lipid absorption is different from that of the satiating effects of duodenally infused fats. These results are consistent with the hypothesis that the satiating effect of fats infused into the small intestine occurs before entry of absorbed fats into the blood and is not dependent on recently absorbed circulating fat.