title: Expression and function of sodium transporters in two opossum kidney cell clonal sublines.
abstract: The present study describes characteristic features of two clonal subpopulations of opossum kidney (OK) cells (OK(LC) and OK(HC)) that are functionally different but morphologically identical. The most impressive differences between OK(HC) and OK(LC) cells are the overexpression of Na+-K+-ATPase and type 3 Na+/H+ exchanger by the former, accompanied by an increased Na+-K+-ATPase activity (57.6 +/- 5.6 vs. 30.0 +/- 0.1 nmol P(i). mg protein(-1). min(-1)); the increased ability to translocate Na+ from the apical to the basolateral surface; and the increased Na+-dependent pH(i) recovery (0.254 +/- 0.016 vs. 0.094 +/- 0.011 pH units/s). Vmax values (in pH units/s) for Na+-dependent pHi recovery in OK(HC) cells (0.00521 +/- 0.0004) were twice (P < 0.05) those in OK(LC) (0.00202 +/- 0.0001), with similar Km values (in mM) for Na+ (OK(LC), 21.0 +/- 5.5; OK(HC), 14.0 +/- 5.6). In addition, we measured the activities of transporters (organic ions, alpha-methyl-D-glucoside, L-type amino acids, and Na+ and enzymes (adenylyl cyclase, aromatic L-amino acid decarboxylase, and catechol-O-methyltransferase). The cells were also characterized morphologically by optical and scanning electron microscopy and karyotyped. It is suggested that OK(LC) and OK(HC) cells constitute an interesting cell model for the study of renal epithelial physiology and pathophysiology, namely, hypertension.
authors.affiliation: Institute of Pharmacology and Therapeutics, Faculty of Medicine, 4200-319 Porto, Portugal.
authors.forename: Pedro
authors.initials: P
authors.lastname: Gomes
authors.forename: Jing
authors.initials: J
authors.lastname: Xu
authors.forename: Paula
authors.initials: P
authors.lastname: Serrão
authors.forename: Sofia
authors.initials: S
authors.lastname: Dória
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Jose
authors.forename: Patrício
authors.initials: P
authors.lastname: Soares-da-Silva
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D001142:Aromatic-L-Amino-Acid Decarboxylases / Q000378:metabolism; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002394:Catechol O-Methyltransferase / Q000378:metabolism; D002999:Clone Cells; D004232:Diuretics / Q000494:pharmacology; D004847:Epithelial Cells / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D006977:Hypertension, Renal / Q000378:metabolism; D015151:Immunoblotting; D007668:Kidney / Q000166:cytology*; D018374:LLC-PK1 Cells; D007930:Leucine / Q000493:pharmacokinetics; D007980:Levodopa / Q000493:pharmacokinetics; D008757:Methylglucosides / Q000493:pharmacokinetics; D008855:Microscopy, Electron, Scanning; D009893:Opossums; D010281:Parathyroid Hormone / Q000494:pharmacology; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D013552:Swine; D010130:p-Aminohippuric Acid / Q000493:pharmacokinetics
chemical_list: D004232:Diuretics; D008757:Methylglucosides; D010281:Parathyroid Hormone; D000074083:Sodium-Hydrogen Exchanger 3; D017923:Sodium-Hydrogen Exchangers; D007980:Levodopa; C027020:methylglucoside; D000584:Amiloride; D002394:Catechol O-Methyltransferase; D001142:Aromatic-L-Amino-Acid Decarboxylases; D000254:Sodium-Potassium-Exchanging ATPase; D007930:Leucine; C039614:ethylisopropylamiloride; D010130:p-Aminohippuric Acid