[Time-course changes in the alkenyl and acyl chain composition of plasmalogens from the heart and kidneys of rats ingesting trielaidin]

Abstract

Weaned rats were fed for 7 or 32 days a semi-purified diet containing 10% of fat supplement in which elaidic acid accounted for 64.5% of total fatty acids. Alkenyl groups from plasmalogens of kidney and heart mitochondria were analysed as their alkyl-substituted dioxane derivatives by gas liquid chromatography (GLC). Acyl chains of total and individual phospholipids (phosphatidylcholine: PC; phosphatidylethanolamine: PE, diacyl and alkenyl-acyl forms; phosphatidylinositol: PI; cardiolipin: CL) were also analysed by GLC. Maximum level of elaidic acid incorporation was attained after only one week on the experimental diet in either total or individual phospholipids. Heart mitochondria phospholipids contained about 40% more trans-monounsaturated acids (20.9%) than kidney mitochondria phospholipids (12.5%) after one month. trans-Monounsaturated acids (t-18: 1 plus t-16: 1 acids) were incorporated in individual phospholipids from both organs in decreasing order: PI greater than PE (total) greater than PC much greater than CL. The order of incorporation of elaidic acid seemed to be related to the content of stearic acid in these phospholipids when the diet was devoid of elaidic acid (PI greater than PE greater than PC much greater than CL). The content of elaidic acid in alkenyl-acyl-glycerophosphoethanolamine (alkenyl-acyl-GPE) was the same (6% of total fatty acids) in both organs. The time-course incorporation of trans-monounsaturated alkenyl chains was different. After one week on the elaidic acid-enriched diet, they represented only 65% (kidney) or 43% (heart) of the values reached after one month. At the end of the feeding period, the trans-monounsaturated alkenyl chains were also about 40% less in total plasmalogens from kidney mitochondria (27.8%) than from heart mitochondria (46%). trans-Monounsaturated acyl chains were incorporated at a higher rate in the 2-position of alkenyl-acyl-GPE than trans-monounsaturated alkenyl chains in their 1-position. Our results confirm the unique observation of Kramer et al. (1985) who noticed that the fatty acid composition of phospholipids was much more rapidly equilibrated than the alkenyl chain composition of plasmalogens (1 week vs 2-3 weeks) from heart of rats fed diets supplemented with different oils.