出版社：American Society for Biochemistry and Molecular Biology
摘要：Chylomicrons labeled with C14-glycerol-H3-palmitic acid were obtained from the cannulated thoracic duct of a rat given C14-glycerol triolein and H3-palmitic acid. The chylomicrons were injected intravenously into male rats and the labeling of liver, heart, and adipose tissue was studied at various time intervals from 5 to 160 min. The conclusion is that the major part of the chylomicron glyceride leaves the circulating blood without previous hydrolysis. Evidence for this conclusion is that no appreciable amount of label was found in the plasma di- or monoglycerides and that the label passing through the plasma free fatty acid (FFA) pool during the clearing of the chylomicrons could not account for more than 10–15% of the total fatty acid label cleared. The liver triglycerides showed a C14/H3 ratio close to 1.0 during the first 10 min. The ratio then declined rapidly. The conclusion is that chylomicron glyceride is taken up intact by the liver, but is rapidly metabolized with re-esterification of the fatty acids to unlabeled glycerol. In the heart and the adipose tissue, the C14/H3 ratio decreased more rapidly. The suggestion is that in these tissues the loss of glycerol may occur during the penetration of the glyceride into the cell, but without mixing of the fatty acids into the plasma FFA pool. At 20 min, when most of the chylomicron label had disappeared from the blood, 35% of the recovered fatty acid radioactivity was found in the liver and 10% in the adipose tissue.
