The pH-dependence of efflux ratios determined with bidirectional transport assays across cellular monolayers

IF 5.2 2区 医学 Q1 PHARMACOLOGY & PHARMACY
Soné Kotze , Kai-Uwe Goss , Andrea Ebert
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引用次数: 0

Abstract

MDCK/Caco-2 assays serve as essential in vitro tools for evaluating membrane permeability and active transport, especially mediated by P-glycoprotein (P-gp). Despite their utility, challenges remain in quantifying active transport and using the efflux ratio (ER) to determine intrinsic values for active efflux. Such an intrinsic value for P-gp facilitated efflux necessitates knowing whether this transporter transports the neutral or ionic species of a compound. Utilising MDCK-MDR1 assays, we investigate a method for determining transporter substrate fraction preference by studying ER pH-dependence for basic, acidic and non-dissociating compounds. These results are compared with model fits based on various assumptions of transporter species preference. As an unexpected consequence of these assays, we also give evidence for an additional influx transporter at the basolateral membrane, and further extend our model to incorporate this transport. The combined influences of paracellular transport, the previously unaccounted for basolateral influx transporter, as well as potential pH effects on the transporter impedes the extraction of intrinsic values for active transport from the ER. Furthermore, we determined that using inhibitor affects the measurement of paracellular transport. While clear indications of transporter species preference remain elusive, this study enhances understanding of the MDCK system.

Abstract Image

跨细胞单层双向转运实验测定的外流比率与 pH 值的关系
MDCK/Caco-2 试验是评估膜通透性和主动转运(尤其是 P-glycoprotein (P-gp)介导的转运)的重要体外工具。尽管它们很有用,但在量化主动转运和使用外流比(ER)确定主动外流的内在值方面仍存在挑战。要确定 P-gp 促进外流的内在值,就必须知道这种转运体是转运化合物的中性物质还是离子物质。利用 MDCK-MDR1 试验,我们研究了一种确定转运体底物部分偏好的方法,即研究ER 对碱性、酸性和非解离化合物的 pH 依赖性。这些结果与基于各种转运体物种偏好假设的模型拟合结果进行了比较。作为这些试验的一个意外结果,我们还提供了基底侧膜上另一种流入转运体的证据,并进一步扩展了我们的模型,以纳入这种转运。细胞旁转运、之前未考虑的基底侧流入转运体以及潜在的 pH 值对转运体的影响共同阻碍了从 ER 提取活性转运的内在值。此外,我们还确定使用抑制剂会影响细胞旁转运的测量。虽然关于转运体物种偏好的明确指示仍然难以捉摸,但这项研究加深了人们对 MDCK 系统的了解。
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来源期刊
International Journal of Pharmaceutics: X
International Journal of Pharmaceutics: X Pharmacology, Toxicology and Pharmaceutics-Pharmaceutical Science
CiteScore
6.60
自引率
0.00%
发文量
32
审稿时长
24 days
期刊介绍: International Journal of Pharmaceutics: X offers authors with high-quality research who want to publish in a gold open access journal the opportunity to make their work immediately, permanently, and freely accessible. International Journal of Pharmaceutics: X authors will pay an article publishing charge (APC), have a choice of license options, and retain copyright. Please check the APC here. The journal is indexed in SCOPUS, PUBMED, PMC and DOAJ. The International Journal of Pharmaceutics is the second most cited journal in the "Pharmacy & Pharmacology" category out of 358 journals, being the true home for pharmaceutical scientists concerned with the physical, chemical and biological properties of devices and delivery systems for drugs, vaccines and biologicals, including their design, manufacture and evaluation. This includes evaluation of the properties of drugs, excipients such as surfactants and polymers and novel materials. The journal has special sections on pharmaceutical nanotechnology and personalized medicines, and publishes research papers, reviews, commentaries and letters to the editor as well as special issues.
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