Metabolism of polyunsaturated fatty acids by rabbit reticulocytes.
Rabbit reticulocytes obtained by repeated bleeding metabolize exogenous [1-14C]linoleic acid and [1-14C]arachidonic acid by three different pathways. 1. Incorporation into cellular lipids: 50% of the fatty acids metabolized are incorporated into phospholipids, mainly phosphatidylcholine (32.8%) but also into phosphatidylethanolamine (12%), whereas about 10% of the radioactivity was found in the neutral lipids (mono- di- and triacylglycerols, but not cholesterol esters). 2. Formation of lipoxygenase products: 30% of the fatty acids metabolized are converted via the lipoxygenase pathway mainly to hydroxy fatty acids. Their formation is strongly inhibited by lipoxygenase inhibitors such as 5,8,11,14-eicosatetraynoic acid or nordihydroguaiaretic acid. Inhibition of the lipoxygenase pathway results in an increase of the incorporation of the fatty acids into cellular lipids. 15-Hydroxy-5,8,11,13(Z,Z,Z,E)eicosatetraenoic acid and 13-hydroxy-9,11(Z,E)-octadecadienoic acid are incorporated by reticulocytes into cellular lipids and also are metabolized via beta-oxidation. The metabolism of arachidonic acid and linoleic acid is very similar except for a higher incorporation of linoleic acid into neutral lipids. 3. beta-Oxidation of the exogenous fatty acids: about 10% of the polyenoic fatty acids are metabolized via beta-oxidation to 14CO2. Addition of 5,8,11,14-eicosatetraynoic acid strongly increased the 14CO2 formation from the polyenoic fatty acids whereas antimycin A completely abolished beta-oxidation. Erythrocytes show very little incorporation of unsaturated fatty acids into phospholipids and neutral lipids. Without addition of calcium and ionophore A23187 lipoxygenase metabolites could not be detected.
D000818:Animals; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000097:blood; D002855:Chromatography, Thin Layer; D005231:Fatty Acids, Unsaturated / Q000097:blood*; D006868:Hydrolysis; D066298:In Vitro Techniques; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000097:blood; D008055:Lipids / Q000097:blood; D008084:Lipoxygenase / Q000097:blood; D010084:Oxidation-Reduction; D010743:Phospholipids / Q000097:blood; D011817:Rabbits; D012156:Reticulocytes / Q000378:metabolism*
D001095:Arachidonic Acids; D005231:Fatty Acids, Unsaturated; D008041:Linoleic Acids; D008055:Lipids; D010743:Phospholipids; D016718:Arachidonic Acid; D019787:Linoleic Acid; D008084:Lipoxygenase