Journal of Lipid Research, Vol 24, 854-860, Copyright © 1983 by Lipid Research, Inc.
Evaluation of an isotope ratio method for measuring biliary cholesterol secretion
JR Crouse, MD Wilson and DS Weaver
We have evaluated an isotope ratio method for measuring biliary cholesterol
secretion. Secretion was measured in eight nonhuman primates by analysis of
radioactivity of feces and plasma 4 weeks after intravenous administration
of a single dose of [3H]cholesterol. For the test, [14C]cholesterol was fed
in known amounts daily for 10 days. The ratio of isotopes in feces (14C/3H)
was equivalent to the ratio of total radioactivity that entered the
intestine from diet and bile. Assuming biliary cholesterol specific
activity equals plasma cholesterol specific activity, the mass of
cholesterol secreted daily in the bile could be calculated. In paired
experiments in four animals we were able to directly compare biliary
secretion by the new method with mass measurement by intraduodenal
intubation (Grundy, S. M., and A. L. Metzger. 1972. Gastroenterology. 52:
2100-1216). The two methods correlated well in these four animals (r =
0.97). We further noted that bile secretion by the new method (eight
animals) and by the mass method (four animals) correlated well with body
weight (r = 0.94 for weight vs secretion by the isotope ratio method; r =
0.97 for weight vs secretion by the mass ratio method). Ranges of body
weight and secretion for the eight animals were 4.2-13.1 kg and 3.6-11.4
mg/hr, respectively. The slopes of the two regression lines for body weight
vs. secretion measured by the two methods did not differ significantly from
one another (F(1.8) = 1.42; 0.25 less than P less than 0.50).(ABSTRACT
TRUNCATED AT 250 WORDS)
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