INCORPORATION OF POSITIONAL ISOMERS OF CIS-OCTADECENOIC AND TRANS-OCTADECENOIC ACIDS INTO ACYL MOIETIES OF RAT-TISSUE LIPIDS

Rats fed a partially hydrogenated soybean oil for 12 weeks were found to contain each of the positional isomers of cis- and trans-octadecenoyl moieties of dietary triacylglycerols in cholesteryl esters, triacylglycerols, and diacylglycerophosphocholines of liver, heart, and serum. cis-9-Octadecenoic acid was selectively esterified in the cholesteryl esters of liver and serum, whereas large proportions of trans-9-Octadecenoic acid were incorporated into cholesteryl esters of heart, cis-9-Octadecenoic acid was also selectively esterified in the triacylglycerols of each tissue, while the individual trans-octadecenoic acids were incorporated into the tissue triacylglycerols in ratios similar to their relative proportions in the dietary triacylglycerols. In the triacylglycerols of each tissue, cis-9-octadecenoic acid was preferentially esterified at position 2, whereas each of the trans-11- to trans-15-octadecenoic acids was preferentially incorporated into positions 1, 3. Relatively little cis-9- or cis-11-octa-decenoic acid, and correspondingly large proprtions of trans-9- and each of the trans-11- to trans-15-octadecenoic acids were incorporated into diacylglycerophosphocholines of each tissue, while the traras-10-octadecenoic acid was distinctly excluded from these lipids. In the diacylglycerophosphocholines, both cis-9- and cis-11-octadecenoic acids were selectively esterified at position 2, whereas each of the trans-octadecenoic acids was selectively incorporated into position 1. © 1979.