Journal of Lipid Research, Vol 28, 1129-1136, Copyright © 1987 by Lipid Research, Inc.
Intestinal cholesterol absorption in the chyluria model
SQ Doi, H Meinertz, K Nilausen, EC Faria and EC Quintao
Department of Internal Medicine, University of Sao Paulo Medical School, Brazil.
Isotopic methods for the measurement of dietary cholesterol absorption were
compared with the lymph cholesterol balance procedure in filarial chyluria
patients. After a single intravenous injection of radioactive cholesterol,
absorption was found to be 746 +/- 136 mg/day by method I, which is based
upon the fecal endogenous neutral steroid mass measurement, and 471 +/- 135
mg/day by the simultaneously measured lymph/plasma ratio of cholesterol
specific activity (dpm/mg). The corresponding value, determined as the
difference between lymph cholesterol transport on a cholesterol-containing
diet (1500 mg) and on a cholesterol-free diet, was 622 mg/day. When
radioactive cholesterol (1487 mg/day) was fed daily to a second patient,
absorption determined by isotopic fecal recovery (353 mg/day) matched that
obtained by the lymph balance procedure (326 mg/day). Transudation of
plasma cholesterol into the intestinal lymph, estimated by the single
intravenous injection of radioactive beta-sitosterol, was independent of
both the luminal content of plant sterols and the absorption of dietary
cholesterol. The absorption of endogenous cholesterol was calculated by: 1)
subtracting the cholesterol originating from plasma (transudation) together
with the absorbed dietary cholesterol found in lymph from the total mass of
cholesterol transported in lymph, and 2) the lymph balance method, i.e.,
after interrupting the endogenous cholesterol mucosal uptake by
beta-sitosterol feeding (9 g/day) while on a cholesterol-free diet.
Endogenous cholesterol was preferentially absorbed compared to dietary
cholesterol, but there was no competition for absorption. The major portion
of dietary cholesterol found in lymph was esterified, but esterification
was not a prerequisite for absorption.