Jazrawi R P, Ferraris R, Bridges C, Northfield T C
Department of Medicine, St. George's Hospital Medical School, London, United Kingdom.
Gastroenterology. 1988 Jul;95(1):164-9. doi: 10.1016/0016-5085(88)90306-x.
The "apparent" fractional turnover rate of the gamma-labeled bile acid analogue 75selenohomocholic acid-taurine (75SeHCAT) was assessed from decline in radioactivity over the gallbladder area on 4 successive days using a gamma-camera, and was compared in the same subjects with the fractional turnover rate of the corresponding natural bile acid, cholic acid-taurine, labeled with 14C ([14C]CAT) using the classical Lindstedt technique. Very similar results were obtained in 5 healthy individuals (coefficient of variation 4.8%, medians 0.35 and 0.34, respectively). By contrast, the fractional deconjugation rate assessed from zonal scanning of glycine- and taurine-conjugated bile acids on thin-layer chromatography was much less for 75SeHCAT than for [14C]CAT (0.02 and 0.13, respectively; p less than 0.05). The fractional rate for deconjugation plus dehydroxylation was also determined by zonal scanning, and gave lower values for 75SeHCAT than for [14C]CAT (0.02 and 0.12, respectively; p less than 0.05). There was a striking similarity between the fractional rate for deconjugation alone and that for deconjugation plus dehydroxylation for both bile acids in individual samples (r = 0.999, p less than 0.001), suggesting that these two processes might occur simultaneously and probably involve the same bacteria. We conclude that our scintiscanning technique provides an accurate, noninvasive method of measuring fractional turnover rate of a bile acid in humans, and that the finding that 75SeHCAT remains conjugated with taurine during enterohepatic recycling means that absorption should be specific for the ileal active transport site, thus rendering it an ideal substance for assessing ileal function.
通过γ相机连续4天监测胆囊区域放射性的下降情况，评估γ标记的胆汁酸类似物75硒高胆酸 - 牛磺酸（75SeHCAT）的“表观”分数周转率，并使用经典的林德施泰特技术，将同一受试者中相应天然胆汁酸胆酸 - 牛磺酸（[14C]CAT）的分数周转率与之进行比较。5名健康个体得到了非常相似的结果（变异系数为4.8%，中位数分别为0.35和0.34）。相比之下，通过薄层色谱法对甘氨酸和牛磺酸结合胆汁酸进行区域扫描评估的75SeHCAT的分数去结合率远低于[14C]CAT（分别为0.02和0.13；p<0.05）。去结合加脱羟基的分数率也通过区域扫描测定，75SeHCAT的值低于[14C]CAT（分别为0.02和0.12；p<0.05）。在个体样本中，两种胆汁酸单独去结合的分数率与去结合加脱羟基的分数率之间存在显著相似性（r = 0.999，p<0.001），这表明这两个过程可能同时发生，并且可能涉及相同的细菌。我们得出结论，我们的闪烁扫描技术提供了一种准确、无创的方法来测量人体胆汁酸的分数周转率，并且75SeHCAT在肠肝循环过程中仍与牛磺酸结合这一发现意味着吸收应该对回肠主动转运位点具有特异性，因此使其成为评估回肠功能的理想物质。
