Absorption of palmitic, stearic and oleic acids in the sheep in the presence or absence of bile and/or pancreatic juice

Abstract

SUMMARY1. The absorption of 3H-and "IC-labelled palmitic, stearic and oleic acids under control conditions and in the absence of bile and/or pancreatic juice has been studied in sheep prepared with intestinal cannulae and reentrant fistulation of the thoracic lymph duct.2. Under control conditions the percentage recoveries in thoracic duct lymph of fatty acids introduced into the duodenum were: stearic acid 59-6 + 3-2 (mean + S.E. of mean), palmitic acid 71-1 + 1-2 and oleic acid 80'4+ 1*9.3. At the peak of absorption over 90 % of the radioactivity was located in the triglyceride fraction.4. It was calculated that between 1900 and 3800 ml. lymph containing up to 20 g lipid flowed daily from the thoracic duct. The major fatty acids of lymph triglycerides were C16:0 (26 %), C18:0 (39 %) and C1,:l (19 %).5. In the absence of pancreatic juice, but in the presence of bile, the absorption of stearic, palmitic and oleic acids was 0-8, 4-1-8-5 and 26% respectively of the dose injected into the duodenum. In the absence of bile but presence of pancreatic juice corresponding values were 0 1-0 5, [1][2][3][4][5][6][7][8] and 7.7 %.6. In the absence of pancreatic juice the total lipid content of thoracic duct lymph fell from 800 to 80 mg % within 4 hr. When bile was also absent the lipid content of lymph fell further to 50 mg %.7. It is concluded that pancreatic juice functions in the lumen of the intestine probably through the production from biliary lecithin of the lysolecithin necessary for the optimum absorption of lipids.

The effect of lecithin on intestinal cholesterol uptake by rat intestine in vitro

“…An important consideration in vivo will be the possible role of lysolecithin, the hydrolytic product of lecithin resulting from the action of Lecithinase A enzyme produced by the pancreas (Deuel, 1955). In a recent study Harrison & Leat (1972) stressed the importance of lysolecithin for fatty acid absorption in the sheep. However, in the rat, there is evidence that biliary lecithin, in contrast to lecithin from other sources, has special properties making it resistant to the action of pancreatic lecithinase (Boucrot, 1972).…”

Origin and Formation of Lymph Lipids in the Sheep

“…Because dietary lipids are hydrolysed in the rumen, the role of pancreatic juice in lipid absorption in the ruminant must be other than the hydrolysis of triglycerides. It has been suggested that pancreatic juice functions by converting biliary lecithin to lysolecithin which may be necessary for optimum solubility of fatty acids in the intestinal lumen [Leat and Harrison, 1969;Harrison and Leat, 1972]. However, it is possible that lysolecithin may function through its ability to enter the mucosal cell (in contrast to lecithin) where it would be esterified to form the lecithin necessary for synthesis of the chylomicron-very low density lipoprotein particle of sheep lymph.…”

“…All Harrison and Leat, 1972]. Two acids were studied simultaneously, 3H palmitic acid (100,uCi) with each of the 14C fatty acids (10 uCi) in turn.…”

“…The free fatty acids are rendered soluble by the action of bile and pancreatic juice and absorbed into the lymphatics where they appear as esterified lipids. Harrison and Leat [1972] showed that radioactively labelled C16: 0, C18: 0 and C18: 1 acids introduced into the duodenum of the sheep are absorbed rapidly into the lymphatics and most of the radioactivity (90%) was associated with the triglyceride fraction. Few quantitative data are available on the synthesis and formation of lymph lipids in the ruminant, and to obtain more information on the origin of lymph lipids the distribution by weight and by radioactivity (i.e.…”

Intestinal absorption and secretion of total and lipid phosphorus in adult sheep fed chopped meadow hay

“…Lennox et al (1968) reported the progressive disappearance of phospholipids through the intestine of sheep. Hydrolysed biliary phospholipids, together with bile salts, would help the micellar solubilization of fatty acids in sheep intestine and enhance the lipid absorption Harrison, 1969, 1974 ;Harrison and Leat, 1972 ;Lough and Smith, 1976). …”