Preferential distribution of non-esterified fatty acids to phosphatidylcholine in the neonatal mammalian myocardium.
Non-esterified fatty acids are used to a limited extent as an energy source in the newborn-mammalian heart. Therefore additional roles for palmitic and oleic acids during this early period of growth and development were investigated in the cultured neonatal-rat heart cell model system. Our results indicate significant differences in nonesterified-fatty-acid metabolism exist in this system in comparison with the adult rat or embryonic chick heart. Initial rates of depletion of palmitate and oleate from serum-free growth medium by heart cells obtained from 2-day-old rats and maintained in culture for 10 or 11 days were 111 +/- 2 and 115 +/- 3 pmol/min per mg of protein respectively. In serum-containing medium, the initial depletion rates were 103 +/- 3 and 122 +/- 4 pmol/min per mg of protein respectively, when endogenous serum nonesterified-fatty-acid concentrations were included in rate calculations. Less than 1% of the intracellularly incorporated fatty acids were found in aqueous products at any time. After 25 h, 15.5% of the initial palmitate was deposited intracellularly in the phosphatidylcholine lipid fraction, 4.2% in the triacylglycerol + fatty-acid-ester fraction and 3.1% in the sphingomyelin fraction. These results contradict the classical view, based on findings with the lipid-dependent adult heart, that exogenous nonesterified fatty acids are directed intracellularly primarily to pathways of oxidation or to storage as triacylglycerol. More importantly, it underscores the significance of exogenous non-esterified fatty acids in membrane biosynthesis of the developing mammalian heart. Included here is a new method for one-dimensional t.l.c. separation of metabolically important polar lipids.
D000818:Animals; D000831:Animals, Newborn / Q000378:metabolism*; D002478:Cells, Cultured; D002855:Chromatography, Thin Layer; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D007424:Intracellular Fluid / Q000378:metabolism; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D019301:Oleic Acid; D009829:Oleic Acids / Q000378:metabolism; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D010713:Phosphatidylcholines / Q000378:metabolism*; D051381:Rats
D005230:Fatty Acids, Nonesterified; D009829:Oleic Acids; D010169:Palmitic Acids; D010713:Phosphatidylcholines; D019301:Oleic Acid; D019308:Palmitic Acid