Abstract
In this study, the expression of members of the organic cation transporter (OCT) family (i.e., OCT 1, 2, 3 as well as OCTN1 and N2) in human bronchial (hBEpC, Calu‐3, 16HBE14o‐) and alveolar (A549) epithelial cells on mRNA and protein level was assessed. Experiments were carried out measuring the effect of time, temperature, pH, sodium concentration and various pharmacological agents on uptake of the cationic fluorophore, ASP+. Bidirectional transport studies of ASP+ across Transwell‐grown cell monolayers were also conducted. All cell types investigated were found positive for OCT1, OCTN1 and OCTN2 expression on mRNA level. OCT3 transcripts were positively identified in Calu‐3 monolayers. No cell type contained transcripts for OCT2. Protein levels were consistent with mRNA expression with the exception of OCT3. A saturable, temperature‐sensitive uptake of ASP+ was observed which was dependent on the pH. Salbutamol, formoterol, verapamil and amantadine resulted in a decrease in ASP+ uptake. In transport studies, 16HBE14o‐ monolayers exhibited net absorption of ASP+, whereas net secretion was found across Calu‐3 monolayers. OCTs are functionally expressed in epithelial cells of the alveolus and bronchi in vitro and might play important roles in the transport of endogenous compounds such as acetylcholine as well as xenobiotics.
Published Version
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