Journal of Lipid Research, Vol. 13, 177-183, March 1972
Copyright © 1972 by Lipid Research, Inc.

Origin of hepatic triglyceride fatty acids: quantitative estimation of the relative contributions of linoleic acid by diet and adipose tissue in normal and ethanol-fed rats

C. L. Mendenhall

Hepatic Research Laboratory and Departments of Medicine and Biochemistry, Indiana University School of Medicine, and Veterans Administration Hospital, Indianapolis, Indiana 46202

The present study demonstrates that the rat liver obtains most of its triglyceride fatty acids from dietary sources. The dietary and adipose tissue contributions of linoleic acid for hepatic triglyceride esterification were shown to be 50.42 and 13.85 µmoles, respectively, during a 4-day period. When ethanol provided 40% of the caloric intake, fatty liver developed and hepatic triglyceride content increased threefold. Under these conditions, the dietary and adipose tissue contributions of linoleic acid were estimated at 192.85 and 10.73 µmoles, respectively. This increase in dietary fatty acid utilization was sufficient to account for the entire increase in esterified hepatic linoleic acid.

Any explanation of these observations must include the high dietary fatty acid utilization in both control and ethanol-treated animals. One possibility is that most dietary lipids first enter a rapidly turning over pool in adipose tissue from which most hepatic triglyceride fatty acids are derived. Another is that dietary fatty acids, incorporated into chylomicrons, are stored separately and used preferentially by the liver as compared with lipids derived from adipose tissue and bound to albumin. The pros and cons of these possibilities are discussed.

Supplementary key words rat liver • rapidly turning over pool • chylomicrons • albumin

Submitted on September 22, 1969
Revised on August 26, 1971
Accepted on September 30, 1971

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