Corn oil (CO) and Sterculic foetida oil (SFO) fed rats were injected with [9, 10-methylene-¹⁴C]sterculic acid. Less than 1% of the label was expired as carbon dioxide. The majority of the label was excreted in the urine as short-chain dicarboxylic acids with an intact cyclopropane ring. The major metabolites for both CO and SFO fed rats were cis-3, 4-methylene adipic acid and cis-3, 4- methylene suberic acid. Sterculic acid must undergo β- and [Greek w]-oxidation to form these urinary metabolites, α-oxidation played a minor role in the formation of cis- and trans-3, 4-methylene pimelic acid. Rats on the SFO diet could metabolize sterculic acid faster than fats on the CO diet. However, both CO and SFO fed rats produced the same urinary metabolites. CO fed rats incorporated more label from sterculic acid into protein and acid soluble liver fractions than SFO fed rats. Less than 0.01% of the label from either group was found in liver lipid sterol or glycerol fractions. There was a tendency for SFO fed rats to metabolize n-[1-¹⁴C] octadecane faster than CO fed rats. This suggests that sterculic acid may induce [Greek w]-hydroxylation of n-octadecane. / Graduation date: 1977

No description available.

published_or_final_version / Biochemistry / Doctoral / Doctor of Philosophy

published_or_final_version / Physiology / Doctoral / Doctor of Philosophy

published_or_final_version / Zoology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / Physiology / Doctoral / Doctor of Philosophy

The suckling rat obtains about 70% of its energy from the catabolism of lipid, compared to only about 25% in the adult rat. In addition, lipids are in great demand for membrane synthesis in the rapidly growing tissues. Thus the suckling rat represents an important system in which to study lipid metabolism. In this dissertation research the following experiments were performed on rats during the suckling period: (1) Determination of the concentration and fatty acid composition of triacylglycerols, cholesteryl esters, phospholipids, and free fatty acids in dam's milk, and in suckling rat lymph, portal plasma, vena cava plasma and liver; (2) Determination of positional distribution of fatty acids among the three different positions in triacylglycerols of milk, lymph, plasma and liver; (3) Isolation of plasma and mesenteric lymph lipoproteins by density gradient centrifugation, and identification of the individual classes of lipoproteins by measurement of their density and by polyacrylamide gel electrophoresis; (4) Determination of the concentration of each lipoprotein by refractometry and determination of the concentration and fatty acid composition of different lipid components in each lipoprotein fraction; (5) Studies of physical properties of the lipoproteins using analytical ultracentrifugation; (6) Determination of apoprotein composition and concentration in each lipoprotein fraction. The results show that the suckling rat consumes a diet which is rich in medium chain fatty acids (35% of total milk fatty acids). Mesenteric lymph triacylglycerols carry a significant amount of these medium chain fatty acids, unlike the adult in which they would be transported as free fatty acids, unlike the adult in which they would be transported as free fatty acids via the portal vein. Medium chain fatty acids are enriched at the sn-3 position in all triacylglycerols. Lymph contains chylomicrons, very low density lipoproteins, and high density lipoproteins, but no low density lipoproteins. Plasma contains all classes of lipoproteins but at concentrations higher than found in the adult, especially low density lipoproteins which are present at levels six times that found in the adult. The plasma very low density lipoproteins have a lipid composition which resembles that of chylomicron remnants. Apoprotein, lipid composition, and electrophoresis patterns show that the plasma lipoproteins in the suckling rat are heterogeneous.

No description available.

No description available.

Simon, S.C., Chiu. / Thesis (M.Ph.)--Chinese University of Hong Kong. / Bibliography: leaves 65-71.