AJP - Gastrointestinal and Liver Physiology, Vol 251, Issue 4 495-G500, Copyright © 1986 by American Physiological Society
Differences in uptake and esterification of saturated analogues of cholesterol by rat small intestine
A. K. Bhattacharyya
Coprostanol and cholestanol are two saturated analogues of cholesterol. The
former, which is the A/B ring isomer of cholesterol, is a nonabsorbable
sterol, whereas the latter, which has an A/B ring configuration closer to
that of cholesterol, is absorbed only half as efficiently as cholesterol.
Intestinal mucosal cell uptake and esterification, two important steps in
absorption, were studied in vivo after feeding the sterols and in vitro
using everted sacs of rat small intestine. The results showed that the
intestinal tissue content of coprostanol, total and esterified, were
significantly lower than that of cholestanol. Total cholesterol
concentration in the intestinal tissue was similar throughout but the
esterified cholesterol content increased significantly throughout the
length of the intestine compared with controls. The study suggests that
cholestanol is absorbable because its uptake and esterification are not
limited, whereas coprostanol is nonabsorbable because its uptake and
esterification are limited in the intestinal mucosa. Also, the two sterols
stimulate the activities of cholesterol esterase, one of the cholesterol
esterifying enzymes, in the intestinal mucosa. The present study along with
previous studies suggests that the structure of the sterol molecule as a
whole appears to be the important determinant for its uptake and
esterification, and probably absorption, in the small intestine.
