Modes of intestinal cholesterol absorption in adult sows.

The nature and distribution of neutral sterols has been determined in the digestive tract of adult Large White sows maintained in a defined biological steady state (constant weight: 70 +/- 5 kg). The semi-synthetic diet contained 0.08 p. 100 cholesterol. Cholesterol was the main sterol of the intestinal contents. From the caecum, it was partially transformed into coprostanol (less than 6 p. 100). Just before the morning meal, the intestinal contents of the sows were rich in cholesterol (532 mg in the small intestine). As in rats, this rapidly renewed cholesterol of endogenous origin was not distributed homogeneously with the exogenous dietary cholesterol. During intestinal cholesterol transit, hydrolysis exceeded esterification. Using the principle of occupancy of every dynamic system, two isotopes were employed to measure the absorption coefficient: cholesterol-4-14C (10 microCi), incorporated into the meal and ingested at one time, and cholesterol-3H (400 microCi), injected intravenously once in a suspension of autologous red blood cells previously labelled in vitro. The absorption coefficient of dietary cholesterol in our experimental conditions reached 57 +/- 4 p. 100. The cholesterol was mainly absorbed in the first-half of the small intestine as in man, whereas in rat it is absorbed in the second-half. This dietary tracer appeared in the general circulation later in swine than in rat or man. After intake of a meal containing the cholesterol tracer, maximal plasma cholesterol radioactivity was reached after 48 hrs in the sows while it is reached after 10-12 hrs in rat or man.