The Incorporation of Ricinoleic Acid into Rat Lymph Lipids ∗

Abstract

One milliliter of ricinoleic acid, triricinolein, or methyl ricinoleate was administered by gastric intubation to thoracic duct-cannulated rats. The lymph was collected over a 48-hr period, the lipids extracted from it, and separated into the various lipid classes by a combination of ion exchange and silicic acid and thin-layer chromatography. The fatty acid composition of each class was determined. The results indicated that ricinoleic acid was present in the triglyceride, diglyceride, monoglyceride, and free fatty acid fractions and reached a peak absorption within 30 hr after administration. Ricinoleic acid was not found in either the phospholipid or cholesterol ester fractions of the lymph lipids. The presence of hydroxy acids in the neutral lipid fractions exerted no particular influence on the general fatty acid composition of the lymph lipids when compared to the lymph lipids from animals that had received a fat-free diet.

Dietary fats which contained long-chain hydroxy acids have been shown to influence the mixed fatty acid composition of rat carcass fat (1). A small percentage of the hydroxy acids was deposited and the remainder converted mainly to monoenoic acids. Both saturated and unsaturated hydroxy acids were apparently converted to monoenes. A larger amount of octadecenoic and hexadecenoic acids seemed to be deposited and a preferential excretion of stearic and linoleic acids appeared to occur in animals fed a source of hydroxy acids in comparison with those fed a source of linoleic acid. The changes in the fatty acid composition which occurred in the lipid classes within the liipds of lymph when ricinoleic acid or its analogs were administered by gastric intubation to thoracic duct-cannulated rats were determined in the present study.

Experimental Methods A permanent thoracic duct cannulation was carried out according to the method of Bollman (2) on male rats with a minimum weight of 400 g. Intramedic polyethylene tubing (PE 50) which had been previously wetted with a 1% heparin solution was inserted into the main thoracic duct of the rat under anesthesia with Nembutal (5 mg/100 g body weight)