Metabolism of long-chain polyunsaturated fatty acids in isolated cardiac myocytes.

ABSTRACT

The uptake and integrated intracellular metabolism of (n - 6) and (n - 3) polyunsaturated fatty acids was studied in isolated rat cardiac myocytes and in the perfused heart. Labeled linolenic acid (183(n - 3)) uptake and its subsequent metabolism into carbon dioxide as well as acylation into lipids was nonsaturable over a substrate range of 0.02 to 0.4 mM. [1-14C]Linoleic acid (182(n - 6)), dihomo-gamma-linolenic acid (203(n - 6)) and arachidonic acid (204(n - 6)) were transported into myocytes at rates similar to those for linolenic acid. Conversely both [1-14C]-gamma-linolenic acid (183(n - 6)) and eicosapentaenoic acid (205(n - 3)) were taken up at a slower rate. Oxidation of 183(n - 6) was 4-5-fold greater when compared with C18-C20 polyunsaturated fatty acids. When myocytes were incubated with labeled 182(n - 6), 183(n - 6), 183(n - 3), 204(n - 6) or 205(n - 3), it was not possible to detect any desaturation or chain-elongation products. Identical results were obtained when hearts were perfused with 1-14C-labeled linoleic acid.