THE INCORPORATION OF PLASMA FREE FATTY ACIDS INTO PLASMA TRIGLYCERIDES IN MAN*

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Abstract
A study was performed to assess the quantitative significance of the conversion of plasma free fatty acids to plasma triglycerides in man. C14 labeled palmitic, oleic, and stearic acids were administered intravenously to 13 fasting male subjects. Thereafter venous blood was sampled at appropriate and frequent intervals over a period of 24 hours. Total plasma free fatty acids, triglycerides, triglyceride activity, cholesterol activity, cholesterol ester activity, and phospholipid activity were determined. It was found that radioactivity appeared almost exclusively in triglycerides during the first 6 hours, and that the disappearance of triglyceride during this period was first-order in type. Later, activity appeared in free cholesterol, cholesterol esters, and phospholipids. From these determinations, plasma triglyceride turnover rates and the fraction of administered radioactive fatty acid initially appearing in plasma as labeled triglycerides were determined. From these observations it was estimated that plasma free acids are the major source of plasma triglycerides and that all three triglyceride fatty acids turn over. It was also found that the fractional turnover rates for triglyceride fatty acid were the same for oleic, stearic, and palmitic acids, but that relatively less stearic acid appeared in triglyceride.