Polyunsaturated fatty acid composition and lipid metabolism in cultured cardiomyocyte and isolated working rat heart

Abstract

The influence of the phospholipid polyunsaturated fatty acid (PUFA) profile on fatty acid metabolism was investigated in cultured cardiomyocytes and isolated working rat hearts. Alteration of the n-6/n-3 PUFA ratio of membrane phospholipids in the whole heart was achieved by feeding the rats a diet containing either sunflower seed oil or linseed oil. Cardiomyocytes were incubated in a medium containing either C18:2n-6 and C20:4n-6 or C18:3n-3 and C20:5n-3. The lipid metabolism was studied in the perfused heart by injection of a bolus of 1- 14C palmitate and further perfusion with non radioactive medium for different periods (0.5 to 5 minutes). Cardiac work and heart rate were monitored throughout the experiment. The cultured cardiomyocytes were incubated for different times (30 to 120 minutes) in a medium containing 1- 14C palmitate. The n-3 PUFA rich treatment provoked a large decrease in the n-6/n-3 ratio of membrane phospholipids that was characterized by an accumulation of C22:6n-3 in the whole heart and shorter chain n-3 PUFA in the cultured cells. In the heart, palmitate oxidation was not affected by the changes in PUFA profile but its incorporation into phospholipids was increased in the n-3 rich group. Neither cardiac work nor heart rate were significantly affected. The n-3 and n-6 rich cardiomyocytes exhibited a similar rate of palmitate oxidation. Thus, the linseed oil-induced changes in the phospholipid PUFA profile of the myocardium did not modify the contractile function nor the fatty acid oxidation.