AJP - Regulatory, Integrative and Comparative Physiology, Vol 235, Issue 1 55-R63, Copyright © 1978 by American Physiological Society
Cholesterol oxidation in primates by simultaneous sterol balance and breath analysis
R. N. Redinger, L. Chow and D. M. Grace
Six female adult rhesus monkeys and baboons with exteriorized enterohepatic
circulations were simultaneously assessed following [26-14C]cholesterol
pulse labeling by 14CO2 breath analysis and combined isotopic and
chromatographic sterol balance during metabolic steady state. Bile acid
synthesis and/or secretion were compared with 14CO2 breath analysis of
cholesterol oxidation during short term physiological changes, and with
total bile acid diversion and feedback inhibition, and biliary tract
obstruction. Cholesterol oxidation by breath analysis compared closely with
acidic sterol losses during steady-state conditions (145.6 +/- 23.9 vs
144.6 +/- 24.4 mg/24 h) and was sensitive enough to detect changes
resulting from diurnal variation and fasting. The 14CO2 test detected
inhibition of bile acid synthesis consequent to bile acid feedback (355 +/-
32 to 88 +/- 31 mg/24 h, P less than 0.001) or biliary tract obstruction
(158 +/- 27 to 60 +/- 28 mg/24 h, P less than 0.05) but underestimated
increased synthesis induced by acute bile diversion (245 +/- 24 vs. 868 +/-
104 mg/24 h, P less than 0.01 at 24 h). Insignificant 14C was detected by
carcass analysis following cessation of exhaled 14CO2.
