Non-Clinical Safety, Pharmaceuticals Division, F. Hoffmann-La Roche Ltd., Grenzacherstrasse 124, B70/R130, CH-4070 Basel, Switzerland.
Pharm Res. 2012 Jul;29(7):1832-42. doi: 10.1007/s11095-012-0707-7. Epub 2012 Feb 22.
Physiologically based models, when verified in pre-clinical species, optimally predict human pharmacokinetics. However, modeling of intestinal metabolism has been a gap. To establish in vitro/in vivo scaling factors for metabolism, the expression and activity of CYP enzymes were characterized in the intestine and liver of beagle dog.
Microsomal protein abundance in dog tissues was determined using testosterone-6β-hydroxylation and 7-hydroxycoumarin-glucuronidation as markers for microsomal protein recovery. Expressions of 7 CYP enzymes were estimated based on quantification of proteotypic tryptic peptides using multiple reaction monitoring mass spectrometry. CYP3A12 and CYP2B11 activity was evaluated using selective marker reactions.
The geometric mean of total microsomal protein was 51 mg/g in liver and 13 mg/cm in intestine, without significant differences between intestinal segments. CYP3A12, followed by CYP2B11, were the most abundant CYP enzymes in intestine. Abundance and activity were higher in liver than intestine and declined from small intestine to colon.
CYP expression in dog liver and intestine was characterized, providing a basis for in vitro/in vivo scaling of intestinal and hepatic metabolism.
生理为基础的模型，在临床前物种中经过验证，能最优地预测人体药代动力学。然而，肠代谢的建模一直存在空白。为了建立代谢的体外/体内比例因子，我们对比格犬的肠和肝中的 CYP 酶的表达和活性进行了特征分析。
采用睾酮 6β-羟化和 7-羟基香豆素葡萄糖醛酸化作为检测肝和肠道组织中微粒体蛋白恢复的标志物，来确定犬组织中微粒体蛋白的丰度。采用多反应监测质谱法对蛋白标志性肽段进行定量，来评估 7 种 CYP 酶的表达。采用选择性标记反应来评估 CYP3A12 和 CYP2B11 的活性。
肝脏中总微粒体蛋白的几何平均值为 51mg/g，在肠道中为 13mg/cm，肠道各段之间无显著差异。CYP3A12 和 CYP2B11 紧随其后，是肠道中最丰富的 CYP 酶。在肝脏中的含量和活性均高于肠道，从小肠到结肠逐渐降低。
对犬肝和肠中的 CYP 表达进行了特征分析，为肠道和肝代谢的体外/体内比例提供了基础。
