Organic cation transport in rabbit alveolar epithelial cell monolayers.

Autor: Shen J; Department of Pharmaceutical Sciences, University of Southern California, Los Angeles 90033, USA., Elbert KJ, Yamashita F, Lehr CM, Kim KJ, Lee VH
Jazyk: angličtina
Zdroj: Pharmaceutical research [Pharm Res] 1999 Aug; Vol. 16 (8), pp. 1280-7.
DOI: 10.1023/a:1014814017316
Abstrakt: Purpose: To characterize organic cation (OC) transport in primary cultured rabbit alveolar epithelial cell monolayers, using [14C]-guanidine as a model substrate.
Methods: Type II alveolar epithelial cells from the rabbit lung were isolated by elastase digestion and cultured on permeable filters precoated with fibronectin and collagen. Uptake and transport studies of [14C]-guanidine were conducted in cell monolayers of 5 to 6 days in culture.
Results: The cultured alveolar epithelial cell monolayers exhibited the characteristics of a tight barrier. [14C]-Guanidine uptake was temperature dependent, saturable, and inhibited by OC compounds such as amiloride, cimetidine, clonidine, procainamide, propranolol, tetraethylammonium, and verapamil. Apical guanidine uptake (Km = 129 +/- 41 microM, Vmax = 718 +/- 72 pmol/mg protein/5 min) was kinetically different from basolateral uptake (Km = 580 +/- 125 microM, Vmax = 1,600 +/- 160 pmol/mg protein/5 min). [14C]-Guanidine transport across the alveolar epithelial cell monolayer in the apical to basolateral direction revealed a permeability coefficient (Papp) of (7.3 +/- 0.4) x 10(-7) cm/sec, about seven times higher than that for the paracellular marker [14C]-mannitol.
Conclusions: Our findings are consistent with the existence of carrier-mediated OC transport in cultured rabbit alveolar epithelial cells.
Databáze: MEDLINE
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