Department of Pharmaceutical Analysis and Drug Metabolism, College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, Zhejiang 310031, People's Republic of China.
Chirality. 2010 Mar;22(3):361-8. doi: 10.1002/chir.20753.
The transport and uptake of individual propranolol (PPL) enantiomers were studied in human intestinal Caco-2 cell monolayers, and a reversed-phase HPLC-UV assay was used for quantitative analysis. S-PPL and R-PPL across Caco-2 cell monolayers was determined in the concentrations range of 10-500 microM in both apical (AP) to basolateral (BL) and BL to AP directions. S-PPL exhibited greater permeability than R-PPL in the AP to BL direction, whereas in the BL to AP direction S-enantiomer transported less than R-enantiomer. Uptake of R-PPL was significantly higher than that of S-PPL either from AP side or from BL side. The statistically significant differences in uptake were observed at the concentrations range from 10 to 50 microM. Furthermore, the apparent Michaelis constant (K(m)) and maximal velocity (V(max)) also showed significant difference between the two enantiomers. Moreover, the AP to BL transport of PPL enantiomer was markedly decreased by lowering the pH of the apical side but it did not affect the stereoselectivity of PPL across Caco-2 cell monolayers. The transport and uptake of PPL in the BL to AP direction was not influenced by several protein inhibitors. The results suggest that PPL enantiomers showed stereoselective transport and uptake across the Caco-2 cell monolayers. A special transport mechanism capable of directing the PPL enantiomers might be present in the Caco-2 monolayers.
我们研究了个体普萘洛尔（PPL）对映体在人肠 Caco-2 细胞单层中的转运和摄取，并采用反相高效液相色谱-紫外检测法进行定量分析。在 10-500μM 的浓度范围内，测定了 S-PPL 和 R-PPL 在 Caco-2 细胞单层中的跨膜转运，方向分别为顶侧（AP）至基底外侧（BL）和 BL 至 AP。在 AP 至 BL 方向，S-PPL 的通透性大于 R-PPL；而在 BL 至 AP 方向，S-对映体的转运量小于 R-对映体。无论是从 AP 侧还是从 BL 侧摄取，R-PPL 的摄取量均明显高于 S-PPL。在 10-50μM 的浓度范围内，摄取存在统计学显著差异。此外，两种对映体的表观米氏常数（K(m)）和最大速度（V(max)）也存在显著差异。此外，降低 AP 侧的 pH 值显著降低了 PPL 对映体的 AP 至 BL 转运，但不影响 PPL 在 Caco-2 细胞单层中的立体选择性。几种蛋白抑制剂对 PPL 对映体从 BL 至 AP 的转运没有影响。结果表明，PPL 对映体在 Caco-2 细胞单层中表现出立体选择性转运和摄取。Caco-2 单层中可能存在一种能够定向 PPL 对映体的特殊转运机制。
