Koljonen Maija, Rousu Katja, Cierny Jakub, Kaukonen Ann Marie, Hirvonen Jouni
Division of Pharmaceutical Technology, University of Helsinki, Helsinki, Finland.
Eur J Pharm Biopharm. 2008 Oct;70(2):531-8. doi: 10.1016/j.ejpb.2008.05.017. Epub 2008 Jun 6.
The purpose of this study was to evaluate passive vs. proton-dependent active transport mechanisms of salicylic acid (SA) and four structurally related anions. Transport was studied across Caco-2 cell monolayers and artificial lipid membranes (PAMPA) under pH-gradient and iso-pH conditions. Kinetic permeability parameters were provided by bidirectional Caco-2 experiments and concentration-dependency measurements. The transport route and putative transporters involved in SA transport were studied using EDTA and several inhibitors. SA and lipophilic 5-chlorosalicylic acid and 2-hydroxy-1-naphthoic acid reached saturation with increasing compound concentration indicating active transport. Permeation of 5-hydroxysalicylic acid and 5-hydroxyisophthalic acid was not saturated indicating passive transport. PAMPA with pure passive diffusion underestimated the transport of SA compared to Caco-2. Opening up the paracellular tight junctions by EDTA did not increase the transport of SA under the pH-gradient conditions confirming the hypothesis of pure transcellular transport of SA. Active transport of SA remained concentration-dependent even without the pH-gradient, and was reduced by the known MCT1 and OATP-B inhibitors and structurally related anions. Overall, several permeability test protocols are needed to obtain a more complete picture of transport properties of salicylic acid and structurally related compounds.
本研究的目的是评估水杨酸（SA）以及四种结构相关阴离子的被动转运与质子依赖性主动转运机制。在pH梯度和等pH条件下，研究了其在Caco-2细胞单层和人工脂质膜（PAMPA）中的转运情况。通过双向Caco-2实验和浓度依赖性测量提供动力学渗透参数。使用EDTA和几种抑制剂研究了SA转运所涉及的转运途径和假定的转运体。SA以及亲脂性的5-氯水杨酸和2-羟基-1-萘甲酸随着化合物浓度增加达到饱和，表明存在主动转运。5-羟基水杨酸和5-羟基间苯二甲酸的渗透未达到饱和，表明为被动转运。与Caco-2相比，具有纯被动扩散的PAMPA低估了SA的转运。在pH梯度条件下，用EDTA打开细胞旁紧密连接并未增加SA的转运，这证实了SA纯跨细胞转运的假设。即使没有pH梯度，SA的主动转运仍保持浓度依赖性，并被已知的MCT1和OATP-B抑制剂以及结构相关阴离子所降低。总体而言，需要几种渗透性测试方案才能更全面地了解水杨酸和结构相关化合物的转运特性。
