Functional characterization of the Organic Cation Transporters (OCTs) in human airway pulmonary epithelial cells.

Functional characterization of the Organic Cation Transporters (OCTs) in human airway pulmonary epithelial cells.
Biochim Biophys Acta. 2015 Apr 13;
Authors: Ingoglia F, Visigalli R, Rotoli BM, Barilli A, Riccardi B, Puccini P, Dall'Asta V
Abstract
Organic cation transporters (OCT1-3) mediate the transport of organic cations including inhaled drugs across the cell membrane, although their role in lung epithelium hasn't been well understood yet. We address here the expression and functional activity of OCT1-3 in human airway epithelial cells A549, Calu-3 and NCl-H441. Kinetic and inhibition analyses, employing [(3)H]1-methyl-4-phenylpyridinium (MPP+) as substrate, and the compounds quinidine, prostaglandine E2 (PGE2) and corticosterone as preferential inhibitors of OCT1, OCT2, OCT3, respectively, have been performed. A549 cells present a robust MPP+ uptake mediated by one high-affinity component (Km ~ 50 μM) which is identifiable with OCT3. Corticosterone, indeed, completely inhibits MPP+ transport, while quinidine and PGE2 are inactive and SLC22A3/OCT3 silencing with siRNA markedly lowers MPP+ uptake. Conversely, Calu-3 exhibit both an high (Km < 20 μM) and a low affinity (Km > 0.6 mM) transport components, referable to OCT3 and OCT1, respectively, as demonstrated by the inhibition analysis performed at proper substrate concentrations and confirmed by the use of specific siRNA. These transporters are active also when cells ar...

Source: Biochimica et Biophysica Acta - April 13, 2015 Category: Biochemistry Authors: Ingoglia F, Visigalli R, Rotoli BM, Barilli A, Riccardi B, Puccini P, Dall'Asta V Tags: Biochim Biophys Acta Source Type: research