Quantification of LDL cholesteryl ester contribution to biliary steroids in the rat.
The proportion of LDL cholesteryl ester converted to biliary steroids was quantified in the rat. The pre-existing pool of bile was allowed to drain for 10-12 h through a bile duct cannula. A single intravenous pulse injection of LDL labelled with [3H]cholesterol linoleyl ester was made, followed by a constant infusion of the same material in order to maintain constant specific radioactivity in plasma. A new steady state was achieved within 6 h and bile samples were then collected hourly until 12 h. Although substantial amounts (53-61 micrograms/h) of cholesteryl ester were released into the liver during LDL catabolism, only a very small fraction (0.8-1.90 micrograms/h) was found in biliary steroids. The proportion of LDL cholesteryl esters contributing to biliary steroids was only 1-2%. These results perhaps explain why perturbations to accelerate bile acid excretion have no effect on plasma LDL cholesterol concentration in the rat.
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Bhattacharya
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Balasubramaniam
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Simons
D000818:Animals; D001646:Bile / Q000032:analysis*; D002788:Cholesterol Esters / Q000032:analysis*; D008078:Cholesterol, LDL / Q000032:analysis; D008077:Lipoproteins, LDL / Q000032:analysis*; D008297:Male; D008433:Mathematics; D051381:Rats; D011919:Rats, Inbred Strains; D013256:Steroids / Q000032:analysis*
D002788:Cholesterol Esters; D008078:Cholesterol, LDL; D008077:Lipoproteins, LDL; D013256:Steroids