The biology of fats. 9. Absorption of conjugated oils and the distribution of conjugated acids in the fat of experimental animals (1st report on the biochemistry of the conjugated acids)

Abstract

9. Literature is reviewed and experiments with the seed oil of Impatiens glandulifera, a species of balsam, which is not toxic and is rich in parinaric acid (octadeca-9: 11: 13: 15-tetraenoic acid) are described. Twelve rats 4 to 7 months old were given 1.5 ml of the oil by stomach tube and were killed from 1/2 to 270 h later. Fat deposits and, in some, liver and kidneys were extracted with hexane and examined for tetraenoic acids by measurement of ultraviolet absorption in the range 285 to 325 m. In another experiment pairs of rats fed on a basal diet of maize 54, wheat 17, casein 7.5, yeast 4, dried skimmed milk 17, NaCl 0.25 and CaCO 3 0.25%, with fresh vegetable twice a week, were given a supplement of 1 g balsam oil daily mixed with the food, for 1, 2 or 3 weeks. Control rats had the diet with 1 g rapeseed oil daily. One rat of each pair was killed at once, the other had a normal diet for 3 weeks before being killed. After a single dose of the oil, mesentery fat at all stages had most and gonadal fat least tetraenoic acid, with omental, perirenal and subcutaneous fats intermediate. Tetraenoic acid appeared in mesentery fat within 1/2 h, rose to a maximum after about 20 h and then declined. The maxima in the fatty tissues came later, in perirenal fat after about 35 h and in the other tissues only after 2 or 3 days. Differences between tissues decreased with time. The concentration of tetraenoic acid in liver was greater than in kidneys and rose to a maximum after 6 h. With continuous feeding on the oil, on the other hand, subcutaneous fat contained more tetraenoic acid than perirenal, and perirenal more than mesentery fat. When the rats were given a normal diet subsequently, the differences were much less. Kidneys contained more than liver. As before, subsequent normal feeding reduced the amounts; in 2 of the 3 rats so fed, no tetraenoic acid was detected in the liver. Results with 6 rabbits given a single dose of 5 ml balsam oil by stomach tube confirmed those with rats. In the rabbits, tetraenoic acid reached a maximum in liver after 15 h, in kidneys after 25 h and in serum after 15 h. It is suggested that when the same fatty acid is given continuously the liver acquires the capacity to metabolise it more rapidly.-W. M. Deans.