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Erucic Acid is Differentially Taken up and Metabolized in Rat Liver and Heart
Author(s) -
Murphy Cameron C.,
Murphy Eric J.,
Golovko Mikhail Y.
Publication year - 2008
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/s11745-008-3168-3
Subject(s) - chemistry , saponification , oleic acid , metabolism , biochemistry , palmitic acid , fatty acid , tracer , phospholipid , chromatography , cholesteryl ester , lipidology , cholesterol , lipoprotein , physics , membrane , nuclear physics
Because X‐linked adrenoleukodystrophy is treated using erucic acid (22:1n‐9), we assessed its metabolism in rat liver and heart following infusion of [14‐ 14 C]22:1n‐9 (170 Ci/kg) under steady‐state‐like conditions. In liver, 2.3‐fold more tracer was taken up as compared to heart, accounted entirely by increased incorporation into the organic fraction (4.2‐fold). The amount of tracer entering the aqueous fraction, which represents β‐oxidation, was not different between groups; however a significantly elevated proportion of tracer was in the heart aqueous fraction. In both tissues, 76% of the radioactivity found in the organic fraction was esterified in neutral lipids, while only about 10% was found esterified into phospholipids. In liver, 56% of lipid radioactivity was found in cholesteryl esters, whereas in heart 64% was found in triacylglycerols. Because 22:1n‐9 can be chain shortened, we assessed tracer metabolism using phenacyl fatty acid derivatives esterified from saponified esterified neutral lipid (triacylglycerol/cholesteryl ester) and phospholipid fractions. In heart esterified neutral lipids, 75% of tracer was recovered as 22:1n‐9 and only 10% as oleic acid (18:1n‐9), while in liver only 25% of the tracer was recovered as 22:1n‐9, while 50% was found as stearic acid (18:0) and 10% as 18:1n‐9. In liver and heart phospholipids, the tracer was distributed amongst the n‐9 fatty acid family. Thus, 22:1n‐9 under went tissue selective metabolism, with conversion to 18:0 the dominant pathway in the liver presumably for export in the neutral lipids, while in heart it was found primarily as 22:1n‐9 in neutral lipids and used for β‐oxidation.