Cowen A E, Korman M G, Hofmann A F, Cass O W
Gastroenterology. 1975 Jul;69(1):59-66.
The metabolism of intravenously injected radiolabeled lithocholate, lithocholylglycine, and their 3alpha-sulfate esters was characterized in healthy subjects. Lithocholate radioactivity was excreted rapidly and predominantly in bile; the excreted radioactivity had the chromatographic properties of glycine and taurine conjugates of lithocholate, of which 60% were sulfated. Lithocholylglycine also was excreted rapidly and predominantly in bile, and 60% of excreted radioacitvity was sulfated. Sulfolithocholate radioactivity was only partially conjugated (about 60%) in association with biliary excretion. Sulfolithocholylglycine was excreted unchanged in bile. Neither sulfated derivative showed appreciable excretion in urine, although both were excreted more slowly in bile than unsulfated free or conjugated lithocholate. The data suggest that unconjugated lithocholate which is absorbed is completely conjugated and partially sulfated before excretion which occurs exclusively in bile. Since sulfation is not complete, some unsulfated lithocholate is always present in bile. This conjugated but unsulfated lithocholate, if reabsorbed, would be again partially sulfated during its next enterohepatic circulation. Thus, the end result of these biotransformations would be for absorbed lithocholate to be excreted in bile mostly, but not entirely as the sulfated conjugates.
在健康受试者中对静脉注射的放射性标记石胆酸盐、石胆酰甘氨酸及其3α-硫酸酯的代谢情况进行了表征。石胆酸盐放射性迅速且主要经胆汁排泄；排泄出的放射性物质具有石胆酸盐的甘氨酸和牛磺酸共轭物的色谱特性，其中60%被硫酸化。石胆酰甘氨酸也迅速且主要经胆汁排泄，排泄出的放射性物质中有60%被硫酸化。硫酸化石胆酸盐放射性在胆汁排泄过程中仅有部分被共轭（约60%）。硫酸化石胆酰甘氨酸在胆汁中未发生变化地排泄。两种硫酸化衍生物在尿液中均未显示出明显排泄，尽管它们在胆汁中的排泄速度均比未硫酸化的游离或共轭石胆酸盐慢。数据表明，吸收的未共轭石胆酸盐在仅经胆汁排泄之前会完全共轭并部分硫酸化。由于硫酸化不完全，胆汁中总会存在一些未硫酸化的石胆酸盐。这种共轭但未硫酸化的石胆酸盐如果被重新吸收，在下一次肠肝循环中会再次部分硫酸化。因此，这些生物转化的最终结果是吸收的石胆酸盐主要经胆汁排泄，但并非完全以硫酸化共轭物的形式排泄。
