COMPARATIVE EFFECTS OF EQUIVALENT INTAKES OF 18-3 (N-3) AND OF MARINE (N-3) FATTY-ACIDS ON RAT CARDIAC PHOSPHOLIPID CONTENTS AND FATTY-ACID COMPOSITIONS

Three groups of male Sprague-Dawley rats were fed for 4 weeks purified diets containing 15% by weight of oil mixtures varying in the nature and content of (n-3) polyunsaturated fatty acids (PUFA) but supplying similar levels of 18:2 (n-6) (10% of the total dietary fatty acids) and of saturated fatty acids (19% of the total fatty acids). The First diet ("Low 18:3") contained small amounts of 18:3 (0.5% of the total fatty acids), the second ("18:3") contained linolenic acid (10% of the total fatty acids) as the only source of (n-3) PUFA and the third one ("LC (n-3)") contained the same amount of long chain (n-3) PUFA (mainly 20:5 and 22:6). Heart phospholipid classes were separated by HPLC, quantified and converted to methyl esters which were analyzed by GLC using glass capillary columns. Dietary consumption of "LC n-3" PUFA resulted in a much higher incorporation of 20:5 (n-3) and 22:6 (n-3) and a much lesser proportion of 20:4 n-6 in heart phosphatidylcholine (PC) and phosphatidylethanolamine (PE) than an equivalent intake of 18:3 (n-3). Dietary "LC n-3" PUFA but not "18:3" reduced the 18:2 (n-6) level and augmented the (n-3) PUFA in heart diphosphatidylglycerol (DPG). Long chain saturated and (n-3) PUFA of sphingomyelin (SPH) are respectively decreased and increased in rats fed marine (n-3) PUFA. Finally, significant increases of the "Unsaturation Index" of PC, PE, DPG and SPH were also seen in rats fed (n-3) PUFA enriched diets. Functional consequences of such fatty acid alterations are discussed. © 1990 Pergamon Press plc.