Incorporation of Cis-octadecenoic Acids into the Rat Liver Mitochondrial Membrane Phospholipids and Adipose Tissue Triglycerides

The incorporation of the dietary cis 18:1(n-12) and cis 18:1(n-10) into liver mitochondrial membrane phospholipids and adipose tissue triglycerides was studied in 4 groups of rats fed diets containing 10 weight percent (wt %) of fat with the following contents of octadecenoic acids: 50% cis 18:1(n-12) + 9% cis 18:1(n-9); 25% cis 18:1(n-12) + 32% cis 18:1(n-9); 50% cis 18:1(n-10) + 10% cis 18:1(n-9); or 54% cis 18:1(n-9). Dietary linoleic acid was 3 wt % in all 4 groups. In the mitochondrial membranes, the isomeric octadecenoic acids were primarily incorporated into the 1-position of phosphatidylcholines and phosphatidylethanolamines at the expense of saturated fatty acids. The maximal incorporations observed in the 1-position of phosphatidylethanolamines were 4.8% 18:1(n-12) and 8.9% 18:1(n-10). No effects on the contents of polyunsaturated fatty acids in the phospholipids were seen. In the adipose tissue, the isomeric octadecenoic acids were incorporated at a level of 13% cis 18:1(n-12) or 23% cis 18:1(n-10), paralleled by a reduction in the content of oleic acid.