Five groups of 20 mice received for 4 months one of the following diets: T, standard diet (T); a, T + cholic acid (0.2%); b, T + cholic acid (0.2%) + beta-sitosterol (2%); c, T + chenodeoxycholic acid (0.2%); d, T + chenodeoxycholic acid (0.2%) + beta-sitosterol (2%). After this time, the cholesterol intestinal absorption and the biliary secretion of lipids were measured. The biliary secretion of cholesterol, the total hepatic cholesterol (23 mg/g liver dry weight), and the intestinal absorption of cholesterol (90% administered dose) were higher in mice fed with cholic acid than in mice fed with chenodeoxycholic acid (hepatic cholesterol, 9.6 mg/g liver dry weight; absorption, 65% administered dose). The addition of beta-sitosterol to the diet supplemented with cholic acid decreased the cholesterol intestinal absorption and the biliary secretion of cholesterol so that both became similar to that obtained with chenodeoxycholic acid. These results indicate that in mice, as in man, cholic acid elicits a higher cholesterol biliary secretion than chenodeoxycholic acid. In this experimental model, the distinct effect on the biliary cholesterol of these two bile salts is due to their specific effects on the intestinal absorption of cholesterol.
Incorporation of [1(14)-C] acetate into cholesterol by subcellular particles from the liver and the small intestine of rats with a biliary diversion and a duodenal perfusion of sodium taurocholate, taurochenodeoxycholate or taurodehydrocholate, was studied in vitro. In the liver, taurochenodeoxycholate prevented the increase of cholesterol synthesis induced by biliary drainage. Taurocholate had no action on cholesterol synthesis at any time, day or night. Intestinal synthesis of cholesterol was reduced by taurocholate and taurochenodeoxycholate but was not modified by taurodehydrocholate infusion.
Diurnal variations of bile lipid concentration were studied in ten patients with a tube in the main bile duct following a cholecystectomy. 5–6 bile samples per 24 h were collected from each patient during 3–40 days. The enterohepatic cycle was not significantly modified since total bile samples did not exceed 40 ml/day. Significant diurnal variations were observed in cholesterol concentration. Changes in lecithin concentration seemed to be similar in seven patients but did not reach the level of significance in any individual patient. Maximal values were observed between 4 and 8 a.m. and minimal values at 4 p.m. Bile salt concentration varied without any circadian periodicity. Mean bile lipid concentration was calculated for each patient. The patients with highest cholesterol concentrations have also the highest mean lecithin concentration. Mean bile salt concentration does not differ much from one patient to another.
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