ROLE OF BILE IN LIPID ABSORPTION 1 1 1 



to choleic acids but having a different ratio of components. Fowweather 557 

 reported the presence of 90% choleic acid together with 10% cholic acid 

 in two enteroliths removed from the intestine of a woman. He concludes 

 that the formation of choleic acid stones requires the concurrence of a 

 number of factors, viz., a mechanical condition which is capable of allow- 

 ing the retention of the precipitated acid, bile which contains more desoxy- 

 cholic acid than is usually present, and also bile in which a considerable 

 proportion of the desoxycholic acid is in the unconjugated form. Hyper- 

 chlorhydria may be an additional factor. 



b. Circulation of the Bile Acids. It has been recognized for a long time 

 that an enterohepatic circulation of bile salts obtains. The amount of bile 

 salts produced de novo would be far too small to account for that needed 

 for the absorption of an appreciable amount of fat if these acids were not 

 used over and over again. Berman and co-workers 558 and Irvin et al. 6b * 

 have concluded that the regulation of the final level of circulating bile 

 acids is accomplished by a state of equilibrium between the rate of syn- 

 thesis and the rate of loss of these acids. This subject has been reviewed 

 recently by Josephson, 4 * who considered the circulation of the bile acids in 

 connection with their production, conjugation, and excretion. 



Since Hoppe-Seyler, 560 in 1863, was able to find only a very small amount 

 of bile salts in the feces, he concluded that they were resorbed by the in- 

 testine. The choleretic effect of bile, when given b}^ mouth or when intro- 

 duced directly into the intestine, was explained by Schiff 561 as the result of 

 the circulation of the bile. The experiments of Tschernoff 562 and of Stadel- 

 mann, 563 carried out somewhat later, proved that the bile acids are absorbed 

 from the intestine and are reexcreted through the liver. 



(a) Absorption of the Bile Acids. When the bile salts, combined with 

 fatty acids as the soluble choleic acids, are absorbed from the lumen of the 

 intestine, they are dissociated almost immediately in the mucosa cells. 

 The fatty acids set free are recombined to form neutral fat, after which they 

 are transported to the liver via the lymph. When bile salts are combined 

 with other lipids, they are also set free within the mucosa cell. 



The bile acids set free may remain for some time in the intestinal wall 



557 F. S. Fowweather, Biochem. J., 44, 607-610 (1949). 



558 A. L. Berman, E. Snapp, A. C. Ivy, and A. J. Atkinson, Am. J. Physiol., 131, 776- 

 782 (1940). 



559 J. L. Irvin, C. G. Johnston, and E. A. Sharp, Am. J. Physiol, 146, 293-306 (1946). 



560 F. Hoppe-Seyler, Arch. path. Anat. Physiol. (Virchow's), 26, 519-537 (1863). 



561 M. Schiff, Arch. ges. Physiol. (Pfliiger's), 8, 598-624 (1870). 



662 W. Tschernoff, Arch. path. Anat. Physiol. {Virchow's), 98, 231-293 (1884). 

 563 E. Stadelmann, Z. Biol, [2], 16 (34), 1-64 (1896). 



