Lymphatic fatty acid absorption profile during 24 hours after administration of triglycerides to rats

In this study we determined in rats the complete 24-h lymphatic fatty acid profile after administration of either rapeseed oil (RO) or rapeseed oil interesterified with 10:0 (RO/C10) with special emphasis on the transition from absorptive to postabsorptive phase. Rats were subjected to cannulation of the main mesenteric lymph duct and the next day oils were administered through a gastric feeding tube. Lymph was collected in 1-h fractions for the following 24 h. The time for maximum lymphatic transport of fatty acids was at 4 h with fast changes in fatty acid composition from the fatty acids of endogenous origin to those of the administered oils. Seven to eight hours after administration the transport was significantly lower than maximum, indicating the change from absorptive to postabsorptive phase. At 24 h after administration of either oil the transport of total fatty acids, palmitic acid (16:0), and linoleic acid (18:2n-6) together with oleic acid (18:1 n-9) after RO had not returned to the transport at baseline. In contrast, the transport of decanoic acid (10:0) and alpha-linolenic acid (18:3n-3) returned to baseline values between 12 and 15 h. This indicated that the absorption of purely exogenous fatty acids (illustrated by 10:0 and 18:3n-3) was complete at 15 h and that the fatty acids transported between 15 and 24 h were derived mostly from endogenous stores.