204 IV. DIGESTION OF LIPIDS OTHER THAN FATS 



proportion of esterified cholesterol present in the bile of dogs is constant, 

 irrespective of whether the sterol is administered in the form of an ester 

 or as the free alcohol, 65 - 66 it has been accepted that a cholesterol-est erase 

 is present in intestinal mucosa. Swell et alP demonstrated the presence 

 of an enzyme in the intestinal mucosa. They concluded that the major 

 source of this enzyme is the pancreatic juice, since the mucosa of rats 

 which had been almost completely depancreatized was found to contain 

 very little of the esterase. However, Stamler and Katz 75 reported that 

 the hypercholesterolemia was greater than normal in depancreatized chicks 

 fed cholesterol. The latter observation indicates that the pancreas is not 

 essential for the absorption of cholesterol from the gastrointestinal tract 

 of the chick. If an esterifying enzyme is required for such absorption, its 

 origin apparently is not in the pancreas. It thus becomes a moot question 

 as to whether or not esterification in the intestinal mucosa is a prerequisite 

 to the absorption of cholesterol. 



(d) Other Factors Concerned with the Absorption of Cholesterol. Lecithin 

 was reported by one group of workers to reduce cholesterol absorption, 

 and by another group of investigators to increase absorption of this sterol. 

 Thus, Kesten and Silbowitz 84 noted that the level of plasma cholesterol 

 was decreased in rabbits fed high levels of lecithin together with cholesterol. 

 On the other hand, Stamler and co-workers 85 observed that choline and 

 inositol increased rather than decreased the level of plasma cholesterol in 

 chicks fed on this sterol. Peterson and associates 76 also concluded that 

 the administration of soy lecithin concomitantly with cottonseed oil and 

 cholesterol to chicks caused a somewhat greater increase in plasma chole- 

 sterol than Avas noted when the same diet was given but without lecithin. 

 It is not known whether these conflicting findings are to be ascribed to the 

 fact that they were obtained on different species, or whether the lack of 

 agreement might be related to differences in the amount of the lecithin 

 dosage employed. The effect of sterols other than cholesterol on the 

 absorption of the latter compound is discussed on page 270. 

 . b. The Effect of Cholesterol on the Absorption of Fatty Acids. There 

 is some evidence that cholesterol may aid in the absorption of fatty acids. 

 Brockett and associates 86 found that, when fat was ingested, not only 

 did a marked rise in the total fatty acids and some increase in the lipid 

 phosphorus in thoracic lymph occur, but also a considerably higher level 



83 L. Swell, J. E. Byron, and C. R. Treadwell, J. Biol. Chem., 186, 543-548 (1950). 



84 H. D. Kesten and R. Silbowitz, Proc. Soc. Exptl. Biol. Med., 49, 71-73 (1942). 



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



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

 (1934) 



