TRIGLYCERIDES AND FATTY ACIDS 187 



injury due to x-irradiation/^^ unless it is supplemented by linoleate. 

 Deuel et al.^^^ noted a similar relationship between linolenate and linoleate 

 employed as supplements in the case of fasting rats and lactating rats on a 

 fat-free diet. Holman^^"*'^^^ is of the opinion that the slight amount of 

 tetraenoic acid synthesized in the animal as a result of the administration 

 of linolenate is probably an inactive isomer. The whole subject must be 

 reassessed in view of the recent finding of Thomasson^^* that 7-linolenic 

 acid (6,9,12-octadecatrienoic acid) is the active essential trienoic acid, 

 while ordinary linolenic acid is believed to possess only a slight biopo- 

 tency. 



c. Interconversions of Elaeostearic Acid. Elaeostearic acid, 9,11,13- 

 octadecatrienoic acid, the conjugated counterpart of linolenic acid, ap- 

 parently undergoes a change, with the loss of a double bond, when given to 

 rats. This change is assumed by Miller and Burr,^^^ on the basis of the 

 fact that the absorption maximum of elaeostearic acid at 270 m^ is lost and 

 a new one appears at 235 m/j, when this fatty acid is metabolized by rats. 

 According to Reiser,^- ^ a similar change of elaeostearic acid to a dienoic 

 acid occurs in the case of the hen fed tung oil, which contains a-elaeo- 

 stearic acid as its principal fatty acid component. In another series of 

 tests, Reiser and co-workers*-^ reported that not only dienoic acids were 

 formed but several other polyunsaturated acids having three to six double 

 bonds. 



d. Interconversions of the More Highly Unsaturated Acids. Informa- 

 tion regarding the presence and fate of polyimsaturated acids higher than 

 arachidonic acid is fragmentary. Holman and Taylor*^' have reported, on 

 the basis of spectrophotometric analyses, that hexaenoic acid is deposited 

 in increased amounts in the heart and brain, and pentaenoic acid in the 

 liver of rats after supplementation with ethyl arachidonate. However, 

 these authors likewise point out that it is questionable whether the more 

 highly unsaturated acids arise from arachidonic acid; it is suggested that 

 the impurities in the tetraenoic acid preparation might have been sufficient 

 to accoimt for the newly-formed 5- and 6-double bonded acids. Reiser*-" 

 noted a significant increase in dienoic acid, but no augmentation hi tri- 

 enoic acid, in growing chicks fed cod-liver oil which was free from dienoic 

 and trienoic acids but which contained more highly unsaturated acids. 



«3« A. L. S. Cheng, T. M. Graham, R. B. Alfin-Slater, and H. J. Deuel, Jr., /. Nutrition, 

 55, 647-653 (1955). 



"9H. J. Deuel, Jr., C. R. Martin, and R. B. Alfin-Slater, /. Nutrition, 57, 297-302 

 (1955). 



""E. S. Miller and G. (). Burr, Proc. Soc. Exptl. Biol. Med., 36, 726-729 (1937). 



«" R. T. Holman and T. S. Taylor, Arch., Biochem., 29, 295-301 (1950). 



