Competition of n-3 and n-6 polyunsaturated fatty acids in the isolated perfused rat heart.

When perfused with exogenous arachidonic acid (AA) or eicosapentaenoic acid (EPA), the rat heart incorporated these fatty acids into phospholipids, chiefly as phosphatidylcholine. The pattern of fatty acid incorporation at any given concentration of fatty acid in the perfusate was not different between n-3 and n-6 polyenoates. When rat hearts were perfused with the same amounts but different mixtures of EPA and AA, the incorporation of EPA showed a marked increase proportional to the EPA/AA ratio present in the perfusate. Results indicated that cardiac muscle phospholipids incorporate n-3 and n-6 polyenoates equally effectively and hence enrichment of n-3 polyenoate can displace AA in the cardiac phospholipid pool.