Henderson G R, St Clair R W
J Lipid Res. 1980 Sep;21(7):854-61.
Six African green monkeys were labeled intravenously with [1,2-(3)H]cholesterol while consuming a cholesterol-free liquid formula diet. The plasma cholesterol specific activity was compared with the specific activity of the biliary cholesterol and bile acids and with the fecal neutral steroids in order to determine whether the traditional isotopic balance method was valid for the calculation of endogenous cholesterol excretion. The specific activity of biliary cholesterol and bile acids averaged 10-15% lower than plasma cholesterol specific activity. Fecal cholesterol and coprostanone specific activities were similar to that of the biliary cholesterol, but the specific activity of fecal coprostanol was approximately 25% lower. This suggests that biliary cholesterol and bile acids were derived from a pool of hepatic cholesterol that did not completely equilibrate with the whole body exchangeable cholesterol pool. In addition, there was further reduction in the specific activity of coprostanol, the major fecal neutral steroid, presumably by cholesterol synthesized in the lower intestine and preferentially converted to coprostanol. As a result, the traditional isotopic balance procedure underestimated endogenous neutral steroid excretion by 46% and bile acid excretion by 31% in African green monkeys fed the cholesterol-free diet. Within 7 days after the addition of 1 mg cholesterol/kcal to the diet, the specific activities of plasma and biliary cholesterol and biliary bile acids were identical and there was no difference in the specific activities of the individual fecal neutral steroids. Thus, the traditional isotopic balance procedure (DPM fecal neutral steroids + bile acids/specific activity [DPM/mg] plasma cholesterol) can be used for calculation of endogenous cholesterol excretion in cholesterol-fed animals during the nonsteady state when plasma cholesterol concentrations are rapidly increasing, as well as after a new steady state has been achieved.-Henderson, G. R., and R. W. St. Clair. Sources of error in the isotopic cholesterol balance method in African green monkeys consuming a cholesterol-free diet.
六只非洲绿猴在食用无胆固醇液体配方饮食时，通过静脉注射[1,2-(3)H]胆固醇进行标记。将血浆胆固醇比活性与胆汁胆固醇和胆汁酸的比活性以及粪便中性类固醇的比活性进行比较，以确定传统的同位素平衡法是否适用于计算内源性胆固醇排泄量。胆汁胆固醇和胆汁酸的比活性平均比血浆胆固醇比活性低10 - 15%。粪便胆固醇和粪甾烷酮的比活性与胆汁胆固醇相似，但粪便粪甾醇的比活性约低25%。这表明胆汁胆固醇和胆汁酸来自肝脏胆固醇池，该池与全身可交换胆固醇池并未完全平衡。此外，主要的粪便中性类固醇粪甾醇的比活性进一步降低，推测是由于下肠道合成的胆固醇优先转化为粪甾醇。结果，在食用无胆固醇饮食的非洲绿猴中，传统的同位素平衡程序低估了内源性中性类固醇排泄量46%，胆汁酸排泄量31%。在饮食中添加1毫克胆固醇/千卡后7天内，血浆和胆汁胆固醇以及胆汁酸的比活性相同，各个粪便中性类固醇的比活性也没有差异。因此，传统的同位素平衡程序（粪便中性类固醇 + 胆汁酸的每分钟衰变数/血浆胆固醇比活性[每分钟衰变数/毫克]）可用于计算胆固醇喂养动物在血浆胆固醇浓度快速增加的非稳态期间以及达到新的稳态后内源性胆固醇的排泄量。 - 亨德森，G. R.，和R. W. 圣克莱尔。食用无胆固醇饮食的非洲绿猴同位素胆固醇平衡法中的误差来源。
