SERUM BILE ACID KINETICS & REGULATION OF BIOSYNTHESIS

这项提案的目的是调查负责 血清和胆汁酸池大小测量的差异 胆汁，以验证使用两个稳定同位素的单一样本血清技术 为了测量胆汁酸的动力学，研究 妊娠和口服避孕药对胆汁酸转化的影响 中间体7α-羟基-4-胆固酮-3-酮，为鹅去氧胆酸 并直接测定胆汁酸的合成 使用18O吸入技术。以下所有实验都将 使用气相色谱/质谱学/稳定同位素进行 比例法。胆汁和血清胆汁酸动力学将在5个月内进行比较 有胆囊症的受试者和5名受试者术后使用 13C-24-CDCA和13C-24-CA。在10名受试者中，我们将比较血清胆汁酸 用双倍同位素稀释法测定同一血清样品的动力学 与使用多样本血清技术的技术相同。在5年内 孕妇和5名服用避孕药的妇女我们将研究 关键胆汁酸中间体的转化， 7α-羟基-4-胆甾烯-3-酮(HCO)与CDCA和CA的反应 和13C-24-CDCA和13-24-CA。HCO组分代谢为CDCA和CDCA 将CA与CDCA和CA的产率进行比较。我们会 5例健康受试者断断续续直接测定胆汁酸合成 通过测定胆汁酸中180的掺入量来测定胆碱胺 吸入180度浓缩气后的羟基。这些 研究将解释我们观察到的池大小之间的差异 从血清和胆汁来衡量。它们将极大地扩展我们的能力 由于受试者依从性的提高和降低而导致的BLE酸动力学 质谱仪实验室中的分析时间。HCO研究可能 准确定位女性改变胆汁酸生物合成的途径 类固醇激素，从而提供关于 女性类固醇激素作用的细胞内定位。这 信息将有助于了解增生性心脏病的发病机制 女性患胆固醇结石的风险，尤其是暴露在高胆固醇环境下的女性 女性类固醇激素浓度。180项研究将验证一项 用于随后测量女性短期影响的技术 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.