The lipid composition of rat liver

Abstract

In a previous publication (Getz & Bartley, 1961) the fatty acid compositions of various intracellular compartments of the rat liver were investigated. This work has now been extended to the fatty acid composition of the different lipid classes of the liver. The data obtained will be used as a basis for comparison of the lipid composition of each of the cell components. This paper reports a compositional analysis of the whole rat liver. EXPERIMENTAL Fractionation of lipids on 8ilicic acid. The techniques of

The lipid composition of phosphorylating ‘digitonin particles’ and water- and saline-extracted mitochondria from rat liver

“…Thus these values indicate that the digitonin treatment results in a loss of about 3-33 moles of phospholipid fatty acid ester/mole of neutrallipid ester lost. The fatty acid distribution in the lysocardiolipin fraction (peak 1) was similar to that of the cardiolipin fraction analysed by Gray & Macfarlane (1958) and Getz & Bartley (1959). The main difference is a somewhat higher proportion of linoloic acid and only half the amount of oleic acid.…”

“…The main difference is a somewhat higher proportion of linoloic acid and only half the amount of oleic acid. By contrast, the lysolecithin peak (peak 8) is very different in fatty acid composition from the mitochondrial lecithin analysed by Getz et al (1962) and Macfarlane et al (1960). Their values showed 58-8 and 61-7 % of unsaturated acids respectively, whereas the lyso compound contained only 47-7 % of unsaturated acids.…”

“…Getz & Bartley (1961) have shown that recoveries as low as 60 % of the lipid may follow the use of trichloroacetic acid to co-precipitate proteins and lipids. Because of the poor recovery of the extracted lipids, the data on these are omitted.…”

“…The dried residue from the determination of dry weights was subsequently used for the determination of protein nitrogen by the Kjeldahl method. The 'direct saponification' and the extraction with ethanol and ether were as described by Getz & Bartley (1961). The proteins and lipids that were extracted by the treatment with water or saline were co-precipitated by adding aq.…”

“…Samples of each phospholipid peak were removed for the determination of amino nitrogen (Cocking & Yemm, 1954), and the remainder of each peak was evaporated to dryness under nitrogen. The subsequent saponification, extraction of the fatty acids and preparation of the methyl esters of the fatty acids by treatment with diazomethane were as described by Getz & Bartley (1961). The aqueous layer after removal of lipids was retained for estimation of choline (Wheeldon & Collins, 1958;Smits, 1957) and glycerol (Hanahan & Olley, 1958), and for identification of the amino acids of the various phospholipids.…”