Dietary cholesterol metabolism in Japanese quail lines selected for plasma cholesterol levels

Dietary cholesterol metabolism was studied, using a single dose of emulsion, per os (test meal), in lines of Japanese quail that were divergently selected for high (HL) and low (LL) plasma total cholesterol. The meal contained [3H] cholesterol, [14C] beta-sitosterol, unlabeled cholesterol, triolein, and bile salt. Recovery of the nonabsorbable beta-sitosterol in the excreta permitted determination of the percentage of cholesterol absorbed. The amounts of [3H] in the plasma, egg yolks, and the excreta neutral and acid sterols were determined. A line-x-time interaction for [3H] in plasma indicated that the level of plasma cholesterol derived from the test meal declined more rapidly in the LL than in the HL. The higher [3H] detected in the excreta acidic sterols of the LL 12 hr after the test meal indicated that bile acid excretion of cholesterol was greater in the LL than in the HL. There were no differences in cholesterol absorption between lines or sexes. Cumulative [3H] radioactivity in the eggs over 18 days following the test meal was higher in the HL yolks; however, this line effect was due to the greater number of eggs produced by the HL. Thus, one of the mechanisms by which the LL maintains low plasma cholesterol levels is by an enhanced excretion of bile acid compared with the HL. The data also suggest that the more severe atherogenic effect of dietary cholesterol observed in the HL could be, in part, due to the longer residence time of cholesterol in circulation.