SERUM BILE ACID KINETICS & REGULATION OF BIOSYNTHESIS

这项建议的目的是调查负责的机制， 观察到血清和 胆汁，以验证使用两种稳定同位素的单样本血清技术 用于胆汁酸动力学的测量，以研究 妊娠和口服避孕激素对胆汁酸转化的影响 中间体，7 α-羟基-4-异戊烯-3-酮，转化为鹅去氧胆酸 （CDCA）和胆酸（CA），并直接测量胆汁酸合成 使用18 O吸入技术。 以下所有实验将 使用气相色谱/质谱/稳定同位素进行 比率测定法 胆汁和血清胆汁酸动力学将进行比较， 胆囊受试者和5例胆囊切除术后受试者使用 13 C-24-CDCA和13 C-24-CA。 在10例受试者中，我们将比较血清胆汁酸 通过双同位素稀释从一份血清样品获得动力学 与使用多样本血清技术的那些技术。 在5 孕妇和5名妇女服用避孕类固醇，我们将研究 关键胆汁酸中间体的转化， 7 α-羟基-4-异戊烯-3-酮（HCO）转化为CDCA和CA，使用氘代HCO 以及13 C-24-CDCA和13-24-CA。 代谢为CDCA的HCO分数， 将CA与CDCA和CA的生产率进行比较。 我们将 直接测量5名健康受试者的胆汁酸合成， 通过测量180掺入胆汁酸的考来烯胺 在吸入富含180的大气后， 这些 研究将解释我们观察到的池大小之间的差异 从血清和胆汁中测量。 它们将极大地扩展我们的能力， 由于受试者依从性改善， 质谱实验室的分析时间。 HCO研究可 指出胆汁酸生物合成的途径，是由女性改变 类固醇激素，从而提供有关 雌性类固醇激素作用的细胞内定位。 这 信息将有助于了解发病机制的增加 女性患胆固醇结石的风险，尤其是那些暴露于高胆固醇的女性。 女性类固醇激素的浓度。 180研究将验证 用于随后测量女性的短期效应的技术 类固醇激素对胆汁酸合成的影响。

The aims of this proposal are to investigate the mechanism responsible for observed differences in bile acid pool size measurements between serum and bile, to validate a single sample serum technique using two stable isotopes for measurement of bile acid kinetics, to investigate the effects of pregnancy and oral contraceptive steroids on conversion of the bile acid intermediate, 7 Alpha-hydroxy-4-cholesten-3-one, to chenodeoxycholic acid (CDCA) and cholic acid (CA) and to directly measure bile acid synthesis using an 18O inhalation technique. All of the following experiments will be performed using gas chromatography/mass spectromatry/stable isotope ratiometry. Biliary and serum bile acid kinetics will be compared in 5 subjects with gallbladders and 5 subjects post-cholecystectomy using 13C-24-CDCA and 13C-24-CA. In 10 subjects we will compare serum bile acid kinetics obtained from one serum sample by double isotope dilution technique with those using the multiple sample serum technique. In 5 pregnant women and 5 women taking contraceptive steroids we will study the conversion of a key bile acid intermediate, 7Alpha-hydroxy-4-cholesten-3-one (HCO) to CDCA and CA, using deuterated HCO and 13C-24-CDCA, and 13-24-CA. The fraction of HCO metabolized to CDCA AND CA will be compared to the production rates of CDCA and CA. We will directly measure bile acid synthesis in 5 healthy subjects on and off cholestyramine by measuring the incorporation of 180 into bile acid hydroxyl groups after inhalation of an 180 enriched atmosphere. These studies will explain the difference we have observed between pool size measured from serum and bile. They will greatly expand our ability to do ble acid kinetics because of improved subject compliance and decreased analytical time in the mass spectrometry laboratory. The HCO study may pinpoint the pathway of bile acid biosynthesis that is altered by female steroid hormones and thereby provide indirect information about the intracellular localization of action of female steroid hormones. This information will aid in understanding the pathogenesis of the increased risk of cholesterol gallstones in women especially those exposed to high concentrations of female steroid hormones. The 180 study will validate a technique for subsequent measurement of the short-term effect of female steroid hormones on bile acid synthesis.