Human cecal bile acids: concentration and spectrum
Human cecal bile acids: concentration and spectrum
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DOI：
10.1152/ajpgi.00027.2007
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发表时间：
2007-07-01
影响因子：
4.5
通讯作者：
Hofmann, Alan F.
中科院分区：
文献类型：
--
作者：
Hamilton, James P.;Xie, Guofeng;Hofmann, Alan F.
为了获得关于人类盲肠内容物中胆汁酸的浓度和光谱的信息，从19名因创伤、他杀、自杀或药物过量等原因非自然死亡的人身上获得了样本。通过3 α -羟基胆汁酸酶法测定胆汁酸浓度；用电喷雾电离质谱法测定胆汁酸的种类，用气相色谱质谱法和液相色谱质谱法测定单个胆汁酸。3 α -羟基胆汁酸浓度（μ mol胆汁酸/ ml盲肠含量）为0.4 +/- 0.2 mM（平均+/- SD）；3-羟基胆汁酸的总浓度为0.6 +/- 0.3 mM。胆汁酸的水浓度（离心后的上清）相同，说明大部分胆汁酸在溶液中。液相色谱-质谱分析显示胆汁酸以非共轭形式存在（90 +/- 9%，平均+/- SD）；磺化、非磺化胆汁酸为7 +/- 5%，非磺化的磺化胆汁酸（甘氨酸或牛磺酸偶联物）为3 +/- 7%。通过气相色谱-质谱法鉴定出10种胆汁酸：脱氧胆酸（34 +/- 16%）、石胆酸（26 +/- 10%）和熊脱氧胆酸（6 +/- 9）及其原胆汁酸前体胆酸（6 +/- 9%）和鹅脱氧胆酸（7 +/- 8%）。此外，部分或全部胆汁酸的3 -羟基衍生物存在，平均占总胆汁酸的27 +/- 18%，表明3 - α -羟基胆汁酸是盲肠内容物的正常成分。在人类盲肠中，胆汁酸的解缀合和去羟基化几乎完成，导致大多数胆汁酸在胶束下和分泌下浓度处于非缀合形式。
To obtain information on the concentration and spectrum of bile acids in human cecal content, samples were obtained from 19 persons who had died an unnatural death from causes such as trauma, homicide, suicide, or drug overdose. Bile acid concentration was measured via an enzymatic assay for 3 alpha- hydroxy bile acids; bile acid classes were determined by electrospray ionization mass spectrometry and individual bile acids by gas chromatography mass spectrometry and liquid chromatography mass spectrometry. The 3 alpha-hydroxy bile acid concentration (mu mol bile acid/ ml cecal content) was 0.4 +/- 0.2 mM ( mean +/- SD); the total 3- hydroxy bile acid concentration was 0.6 +/- 0.3 mM. The aqueous concentration of bile acids ( supernatant after centrifugation) was identical, indicating that most bile acids were in solution. By liquid chromatography mass spectrometry, bile acids were mostly in unconjugated form ( 90 +/- 9%, mean +/- SD); sulfated, nonamidated bile acids were 7 +/- 5%, and nonsulfated amidated bile acids ( glycine or taurine conjugates) were 3 +/- 7%. By gas chromatography mass spectrometry, 10 bile acids were identified: deoxycholic ( 34 +/- 16%), lithocholic ( 26 +/- 10%), and ursodeoxycholic ( 6 +/- 9), as well as their primary bile acid precursors cholic ( 6 +/- 9%) and chenodeoxycholic acid ( 7 +/- 8%). In addition, 3 beta-hydroxy derivatives of some or all of these bile acids were present and averaged 27 +/- 18% of total bile acids, indicating that 3 alpha- hydroxy bile acids are normal constituents of cecal content. In the human cecum, deconjugation and dehydroxylation of bile acids are nearly complete, resulting in most bile acids being in unconjugated form at submicellar and subsecretory concentrations.