13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

The purpose of the present study was to examine the short-term effect of dietary specific structured triacylglycerols (MLM, M = 8:0, L = 18:2n-6), LLL and MMM on the fatty acid composition of brush border membrane (BBM) phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Rats were administered intragastrically a bolus of ML*M, M*LM*, L*L*L* or M*M*M* (* = C-13- labeled fatty acid).

Rats were decapitated 2 hours and 6 hours later, and the fatty acid composition and C-13-enrichment of BBM-PC and -PE were determined. C-13-enriched 18:2n-6 was observed in BBM-PC after intragastric administration of L*L*L* and ML*M, whereas no C-13-labeled fatty acids were recovered after administration of M*LM* or M*M*M*.

Interestingly, no C-13-labeled fatty acids were detected in the BBM-PE fraction. This could be due to a lower turnover of PE than PC and to a different ratio of saturated and unsaturated fatty acids in the two phospholipid pools. Minor effects on BBM-PC and BBM-PE fatty acid profiles (mole-%) were observed.

The present study demonstrated for the first time incorporation of C-13-labeled 18:2n-6 into BBM-PC 2 hours and 6 hours after intragastric administration of L*L*L* or ML*M. This emphasizes the influence of the dietary fatty acid on BBM fatty acid composition and the rapid incorporation of dietary long-chain fatty acids into intestinal enterocyte phospholipids.

Medium-chain fatty acids in a single meal exert only a minor influence on the BBM phospholipid fatty acid profile.