ABSORPTION AND TRANSPORT 365 



absorption of cholesterol, noted by many workers, to their activation of 

 cholesterol esterase. It is believed that one molecule of bile salt and one of 

 cholesterol combine to effect the esterifi(!ation of the fatty acid.^" These 

 \vorkers^^ noted that sodiimi cholate and sodium taurocholate were the 

 most effective of the bile salts hi bringing about the absorption of choles- 

 terol, while sodium desoxycholate was less active, and sodium dehydro- 

 cholate was completely inactive. It is suggested^^ that bile salts function 

 in cholesterol absorption because they provide the necessary co-factor for 

 cholesterol esterase activity. However, all data are not unanimous in in- 

 dicating that esterification is an essential prerequisite for cholesterol ab- 

 sorption, and it remains a moot question whether or not a change in the 

 intestinal mucosa is required to insure absorption. 



It was stated by Peterson et al.^^ that lecithin increases cholesterol ab- 

 sorption. However, Kesten and Silbowitz^' reached the opposite conclu- 

 sion. The level of blood cholesterol also rises when choline or inositol is 

 fed to chicks receiving cholesterol.'*^ This may be interpreted as analogous 

 to the lecithin effect. Aftergood et al.^^ found that the total liver choles- 

 terol content of rats fed a diet containing 15% of lard with 1% cholesterol 

 was significantly decreased by the addition of high amounts of vitamin E. 



Hormones also have an effect on cholesterol absorption. Thus, Coleman 

 and co-workers^* found that, in the case of male rats gonadectomized after 

 sexual maturity and placed on a diet containing 15% cottonseed oil and 1% 

 cholesterol, for six weeks, there was a marked decrease in the cholesterol 

 concentration in the liver, as compared with values obtained for the livers 

 of non-operated animals maintained on the same diet. In the case of 

 gonadectomized females, the cholesterol concentration in the liver increased, 

 as compared with that in unoperated female rats. This sex difference in 

 absorption was also noted by Aftergood et al.^^ For a more detailed reidew 

 of the absorption of cholesterol, the reader is referred to The Lipids, Vol. 

 II, pages 259-268 and 270, 271. 



{2) The Absorption of Sterols Other Than Cholesterol 



In contradistinction to the relative ease with which cholesterol is ab- 

 sorbed from the gastrointestinal tract, it has been considered that many 



*o L. Swell, H. Field, Jr., and C. R. Treadwell, Proc. Soc. Expll. Biol. Med., 84, 417- 

 420(1953). 



<i H. D. Kesten and R. Silbowitz, Proc. Soc. Expll. Biol. Med., 49, 71-73 (1942). 



" J. Stamler, C. Bolene, R. Harris, and L. N. Katz, Circulation, 2, 714-721 (1950). 



*' L. Aftergood, R. B. Alfin-Slater, and H. J. Deuel, Jr., Federation Proc, 16, 541 

 (1956). 



" R. D. Coleman, Yii Min Chen, R. B. Alfin-Slater, and H. J. Deuel, Jr., Federation 

 Proc, 75,234(1956). 



