title: Polarized distribution of oxalate transport systems in LLC-PK1 cells, a line of renal epithelial cells.
abstract: Although oxalate is a major component of kidney stones, the factors affecting renal oxalate handling are poorly understood. This uncertainty stems in part from complexities inherent to available preparations; thus the present studies examined oxalate handling in a simpler model system, LLC-PK1 cells, an epithelial cell line of porcine origin. Initial studies on monolayers in dishes demonstrated that these cells accumulate oxalate via a process or processes sensitive to the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). Subsequent studies using LLC-PK1 monolayers on membrane filters examined the characteristics and distribution of these transporter(s). At the apical surface, DIDS-sensitive uptake was sensitive to [Cl-] but not [SO4(2-)] or [HCO3-] and was unaffected by alterations in pH or membrane potential. At the basolateral surface, oxalate uptake was [Cl-] insensitive but markedly affected by variation in pH, [SO4(2-)], or [HCO3-]. Uptake at the two membrane surfaces was also differentially affected by transport inhibitors and organic acids. Thus LLC-PK1 cells appear to express unique transporters at each membrane surface: oxalate/Cl- exchange at the apical surface and oxalate/SO4(2-) (or HCO3-) exchange at the basolateral surface.
authors.affiliation: Division of Urology and Transplantation Surgery, University of Massachusetts Medical School, Worcester 01655.
authors.forename: H
authors.initials: H
authors.lastname: Koul
authors.forename: S
authors.initials: S
authors.lastname: Ebisuno
authors.forename: L
authors.initials: L
authors.lastname: Renzulli
authors.forename: M
authors.initials: M
authors.lastname: Yanagawa
authors.forename: M
authors.initials: M
authors.lastname: Menon
authors.forename: C
authors.initials: C
authors.lastname: Scheid
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000494:pharmacology; D000818:Animals; D000838:Anions / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002264:Carboxylic Acids / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000494:pharmacology; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D005665:Furosemide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007668:Kidney / Q000378:metabolism*; D007700:Kinetics; D010070:Oxalates / Q000378:metabolism*; D011339:Probenecid / Q000494:pharmacology; D013997:Time Factors
chemical_list: D000838:Anions; D002264:Carboxylic Acids; D002712:Chlorides; D010070:Oxalates; D005665:Furosemide; D011339:Probenecid; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid