LYMPHATIC ABSORPTION OF OXIDIZED CHOLESTEROL IN RATS

The absorption of cholesterol and of cholesterol oxidation products (o xidized cholesterols) was compared in lymph-cannulated rats. We found that the lymphatic absorption of an intragastrically administered, emu lsified lipid meal containing 25 mg of cholesterol or 25 mg of oxidize d cholesterols, within 24 h, was approximately 67 and 30%, respectivel y. The absorption rate individual oxidized cholesterols differed consi derably and was approximately 30% for 7 alpha-hydroxycholesterol, 42% for 7 beta-hydroxycholesterol, 32% for 5 beta-epoxycholesterol, 28% fo r 5 alpha-epoxycholesterol, 15% for cholestanetriol and 12% for 7-keto cholesterol. Moreover, cholesterol oxidation products delayed the abso rption of oleic acid as triolein. Approximately 35 and 48% of choleste rol was recovered in chylomicrons (CM) and very low density lipoprotei n (VLDL), respectively. In contrast, 54 and 40% of the oxidized choles terols was recovered in CM and VLDL, respectively, although there was a significant difference in the distribution of individual oxidized ch olesterols. The results of the present study indicate that oxidized ch olesterols are absorbed to a lesser extent than is cholesterol, that t hey disturb fat absorption and that they distribute differently betwee n lymphatic lipoproteins.