中文摘要：

目的：研究环肽astin C在Caco-2细胞单层模型中的吸收机制。方法：研究astin C在Caco-2细胞单层模型中的双向转运,考察时间、药物浓度对astin C吸收的影响。采用高效液相色谱法检测astin C的浓度,计算其表观渗透系数（Papp）。结果：在Caco-2细胞单层模型中,astin C的吸收随着时间和浓度的增加药物吸收呈近似线性增加;Papp（A→B）明显大于Papp（B→A）,存在方向差异性;astin C不是P-gp的底物。结论：Astin C在Caco-2细胞单层模型中的主要转运机制是AP侧膜转运蛋白所介导的主动转运。

英文摘要：

Objective ： To study the absorption mechanism of the astin C, a cyclopeptide, in Caco-2 cell monolayer model. Method： Caco-2 cell model was established to investigate the bidirectional transport of astin C. The influences of time and drug concentration on the absorption of astin C was observed. Drug concentration was measured by HPLC and the apparent permeability coefficients（Papp） was calculated. Results： The absorption of asitn C in Caco-2 cell monolayer was nearly linear increased in a time and concentration dependent manner. The value of Papp （ A→B ） was much greater than that of Papp （B-~A） indicating astin C was not a substrate of P-gp. Conclusion ： The absorption of astin C in Caco-2 cell mon- olayers is an active transportation mediated by transporter in the AP side.