Journal of Lipid Research, Vol. 6, 84-90, January 1965
Copyright © 1965 by Lipid Research, Inc.
Transfer of fatty acids between triglyceride species in rat adipose tissue
C. H. Hollenberg
McGill University Medical Clinic, The Montreal General Hospital, Montreal, Quebec, Canada
To study the rate of fatty acid transfer between triglyceride species in adipose tissue, palmitate-1-C14 was incorporated into adipose tissue triglyceride by incubation in buffer-glucose. Following extraction, the saturated triglycerides were precipitated in cold alcohol-acetone; this fraction contained over 40% of the incorporated label and 15% of the total tissue palmitic acid. Thus the specific activity of palmitic acid in this fraction was over 4 times that in predominantly unsaturated triglycerides. This relationship was unaltered by further incubation of tissue for 3 hr in fresh medium containing glucose-insulin only, or glucose-insulin plus unlabeled oleic acid.
Similar experiments using as in vivo incubation technique demonstrated that by two weeks after incubation the proportion of radioactivity in the saturated fraction had fallen only from 43 to 34%. This fall was apparently not due to greater fractional turnover of saturated triglycerides or to desaturation of palmitic acid, and thus was the result of slow redistribution of palmitate-C14 between predominantly saturated and unsaturated triglycerides. The data indicate that intermolecular rearrangement of triglyceride fatty acids in adipose tissue occurs slowly, and thus is more likely a result of hydrolysis of triglyceride and reesterification of fatty acids than of rapid, extensive transesterification.
Supplementary key words fatty acids • transesterification • triglyceride • adipose tissue • rat • free fatty acids • palmitate-1-C14 • diglyceride • saturated triglyceride turnover • esterification • lipolysis
Submitted on June 29, 1964
Accepted on September 2, 1964
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