ABSORPTION AND TRANSPORT OF FATS 169 



stein 797 noted a definite increase in blood fatty acids during fat absorption, 

 following a diversion of the thoracic duct lymph. However, other workers 

 such as Zucker, 798 Winter and Crandall, 799 Little and Robinson, 776 and 

 Brockett, Spiers, and Himwich, 800 have presented opposite results. 



The possibility of an alternative pathway for absorption, i.e., the portal 

 vein, is indicated by certain data. The failure to recover approximately 

 40% of fat in the lymphatics as demonstrated in the classic experiments 

 of Munk, 694 and the disappearance of 70% of the fat from the intestine in a 

 case of idiopathic steatorrhea, without an appreciable increase in the fat 

 of the systemic system, could be explained by assuming a partial absorp- 

 tion by this alternative route. 



There seems to be general agreement that the volatile fatty acids may be 

 absorbed via the portal vein, as suggested by Raper. 786 It is also in accord 

 with the report that, although tributyrin is absorbed, none can be detected 

 in the chyle 801 or in the depot fat. 802 Moreover, Eckstein 802 demonstrated 

 that tributyrin was not stored by the rat, while Davis 803 obtained similar 

 results with chickens. However, the latter investigator was able to detect 

 small amounts of tributyrin in the body fat when this triglyceride was in- 

 jected subcutaneously or intraperitoneally. The finding of Bavetta and 

 Deuel, 686 that tributyrin is absorbed in a normal manner by the rat after 

 adrenalectomy, in contradistinction to the depressed absorption of the 

 fats having long-chain fatty acids, has been interpreted by Frazer 645 as 

 indicating that the butyrate is absorbed after hydrolysis; such water- 

 soluble components are believed to take the portal route rather than that 

 via the lymphatics. In later work, Bavetta 687 proved that all water-soluble 

 fatty acids up to caprylic acid are absorbed as satisfactorily after removal 

 of the adrenal glands as when these glands are present ; however, all of the 

 higher fatty acids which are insoluble in water are dependent upon the 

 adrenocortical hormone. Bloom et al. 790 supplied circumstantial evidence 

 that, in addition to the volatile acids (acetic, butyric, and caproic), decanoic 

 acid may also be transported by the portal route, and, to a lesser extent, 

 lauric acid. Although the acids were not isolated from the portal blood, it 

 was shown that their disappearance from the gut was not the result of 



797 H. C. Eckstein, /. Biol. Chem., 62, 737-739 (1924-1925). 



798 T. F. Zucker, Proc. Soc. Exptl. Biol. Med., 17, 89-91 (1920). 



799 1. C. Winter and L. A. Crandall, Jr., /. Biol. Chem., 140, 97-104 (1941). 



800 S. H. Brockett, M. A. Spiers, and H. E. Himwich, Am. J. Physiol., 110, 342-347 

 (1934). 



801 R. H. Hughes and E. J. Wimmer, /. Biol. Chem., 108, 141-144 (1935). 



802 H. C. Eckstein, /. Biol. Chem., 81, 613-628 (1929). 



803 R. E. Davis, J. Biol. Chem., 88, 67-75 (1930). 



