Lecithin Inhibits Fatty Acid and Bile Salt Absorption from Rat Small Intestine In Vivo 1 D.R. SAUNDERS and J. SILLERY, Department of Medicine, University of Washington, Seattle, Washington 98195 ABSTRACT
rapidly through luminal water. We speculated that, in pancreatic insufficiency, lecithins might retard the absorption of FFA as well as of bile salts. To evaluate our speculation, we measured the rate of absorption of a long chain fatty acid (linoleate) and a bile salt (taurocholate) from isolated rat small intestine in vivo in the presence of a commonly occurring lecithin or its hydrolytic product. Water absorption was measured simultaneously because inhibition of water transport might be responsible for depression of solute absorption. Lipids were infused in concentrations which are similar to those in postcibal duodenojejunal contents of patients with pancreatic insufficiency (10).
During digestion of a fatty meal, long chain free fatty acids (FFA) and lecithin are among the lipids solubilized in intestinal contents as mixed micelles with bile salts. We hypothesized that if lecithin were not hydrolyzed, the mixed micelles would be abnormal, and absorption of FFA and bile salts would be depressed. To test this hypothesis, isolated segments of rat small intestine were infused in vivo w i t h micellar solutions of 2mMolar linoleic acid and 10 mMolar taurocholate to which was added 3 mMolar 1-palmitoyl, 2-oleoyl lecithin (a common lecithin in bile and food), or 1-palmitoyl lysolecithin (the hydrolytic product of lecithin). Absorption of FFA and bile salt was measured under steady state conditions using a single-pass technique. Lecithin depressed the rate of FFA absorption by 40% (p
rapidly through luminal water. We speculated that, in pancreatic insufficiency, lecithins might retard the absorption of FFA as well as of bile salts. To evaluate our speculation, we measured the rate of absorption of a long chain fatty acid (linoleate) and a bile salt (taurocholate) from isolated rat small intestine in vivo in the presence of a commonly occurring lecithin or its hydrolytic product. Water absorption was measured simultaneously because inhibition of water transport might be responsible for depression of solute absorption. Lipids were infused in concentrations which are similar to those in postcibal duodenojejunal contents of patients with pancreatic insufficiency (10).
During digestion of a fatty meal, long chain free fatty acids (FFA) and lecithin are among the lipids solubilized in intestinal contents as mixed micelles with bile salts. We hypothesized that if lecithin were not hydrolyzed, the mixed micelles would be abnormal, and absorption of FFA and bile salts would be depressed. To test this hypothesis, isolated segments of rat small intestine were infused in vivo w i t h micellar solutions of 2mMolar linoleic acid and 10 mMolar taurocholate to which was added 3 mMolar 1-palmitoyl, 2-oleoyl lecithin (a common lecithin in bile and food), or 1-palmitoyl lysolecithin (the hydrolytic product of lecithin). Absorption of FFA and bile salt was measured under steady state conditions using a single-pass technique. Lecithin depressed the rate of FFA absorption by 40% (p
