DIETARY-CHOLESTEROL METABOLISM IN JAPANESE-QUAIL LINES SELECTED FOR PLASMA-CHOLESTEROL LEVELS

Dietary cholesterol metabolism was studied, using a single dose of emu lsion, per os (test meal), in lines of Japanese quail that were diverg ently selected for high (HL) and low (LL) plasma total cholesterol. Th e meal contained [H-3] cholesterol, [C-14] beta-sitosterol unlabeled c holesterol, triolein, and bile salt. Recovery of the nonabsorbable bet a-sitosterol in the excreta permitted determination of the percentage of cholesterol absorbed. The amounts of [H-3] in the plasma, egg yolks , and the excreta neutral and acid sterols were determined, A line-x-t ime interaction for [H-3] in plasma indicated that the level of plasma cholesterol derived from the test meal declined more rapidly in the L L than in the HL. The higher [H-3] detected in the excreta acidic ster ols of the LL 12 hr after the test meal indicated that bile acid excre tion of cholesterol was greater in the LL than in the HL. There were n o differences in cholesterol absorption between lines or sexes, Cumula tive [H-3] radioactivity in the eggs over 18 days following the test m eal was higher in the HL yolks; however, this line effect was due to t he grater number of eggs produced by the HL. Thus, one of the mechanis ms by which the LL maintains low plasma cholesterol levels is by an en hanced excretion of bile acid compared with the HL. The data also sugg est that the more severe atherogenic effect of dietary cholesterol obs erved in the HL could be, in part, due to the longer residence time of cholesterol in circulation.