THE EFFECT OF INCREASED INTAKE OF DIETARY -CHOLESTEROL ON BILE-ACIDS AND ON THE CHOLESTEROL-METABOLISM OF THE LIVER

The effect of increased intake of dietary cholesterol on synthesis and biliary secretion of bile acids and cholesterol was investigated in r ats equipped with a permanent bilio-digestive shunt and a venous cathe ter. Cholesterol-rich diet led to an increase in serum cholesterol of no more than 20%, while bile acid synthesis increased by 200% and the bile acid pool by 30%. Cholesterol stored in the liver increased by 30 0%, while the biliary excretion of cholesterol decreased by 50%. After injection of H-3-cholesterol-labeled chylomicron remnants, within the first hour H-3 was secreted as cholesterol and as bile acids to the s ame extent. At later time points more than 90% of H-3 was in the form of bile acids. In cholesterol fed rats the biliary secretion of H-3 wa s raised from 22% to 27% of the injected dose, at any time bile acids being the major metabolite containing H-3. The secretion of H-3-bile a cids was increased by 36%, while: the secretion of H-3-cholesterol was decreased by 42%. In summary, a large proportion of cholesterol carri ed in chylomicron remnants is degraded to bile acids and secreted into the bile. In the rat high dietary intake of cholesterol leads to rais e degradation to bile acids and to decreased biliary excretion of chol esterol.