THE CHARACTERISTICS OF THE PERIPHERAL TRANSPORT OF C14-LABELED PALMITIC ACID *

Abstract
The simultaneous arteriovenous difference of C14-labeled palmitic acid and of total plasma free fatty acid was studied in the human arm and leg during constant intravenous infusion of albumin-bound palmitic acid-1-C14. The results indicated that the label was always taken up by the limb and that the venous level of the label was 10 to 50% less than the arterial level regardless of the vein selected for sampling. The simultaneous venous level of total chemically determined free fatty acid, on the other hand, was often higher than the arterial level and indicated that palmitic acid-1-C14 was extracted by the arm and leg even when there was a net release of total free fatty acids. It is concluded that total chemically determined free fatty acid arteriovenous differences do not provide a reliable index for measurement of uptake or release of this substance in peripheral tissues.