title: Increased Na/H antiport activity and abundance in uremic red blood cells.
abstract: Alterations in red blood cell sodium (Na) transport have been described in chronic renal failure. This study examines the possible impact of uremia on two ouabain-insensitive pathways, the Na/H antiporter and the Cl-/NaCO3- anion exchanger. The Vmax of Na/H antiporter measured as Na influx driven by outward H gradient in acid loaded red blood cells was significantly higher in uremic red blood cells versus controls (60.5 +/- 16.5 vs. 24.5 +/- 5.4 mmol/liter cells/hr, P < 0.025). This increase in activity was associated with an increased abundance of the Na/H antiporter as determined by immunologic analysis using an affinity purified polyclonal antibody to the human NHE-1 isoform of the antiporter. By contrast, the activity of the anion exchanger measured as the DIDS-sensitive lithium (Li) influx was similar in uremic versus control red blood cells (2.10 +/- 0.18 vs. 2.14 +/- 0.20 mmol/liter cells/hr). These experiments, when considered in conjunction with prior studies showing normal Na/Li countertransport in uremia indicate that there is a selective increase in the number of functional Na/H antiporters in uremic red blood cells and that Na/Li countertransport measurements may not be a valid marker for Na/H antiporter activity in red blood cells in patients requiring dialysis for end-stage renal failure.
authors.affiliation: Department of Medicine, Olive View Medical Center Sylmar, California.
authors.forename: D B
authors.initials: DB
authors.lastname: Corry
authors.forename: M L
authors.initials: ML
authors.lastname: Tuck
authors.forename: S
authors.initials: S
authors.lastname: Nicholas
authors.forename: E J
authors.initials: EJ
authors.lastname: Weinman
mesh_terms: D000368:Aged; D002712:Chlorides / Q000097:blood; D004912:Erythrocytes / Q000378:metabolism*; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D017136:Ion Transport; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000097:blood*; D017693:Sodium Bicarbonate / Q000097:blood; D017923:Sodium-Hydrogen Exchangers / Q000097:blood*; D014511:Uremia / Q000097:blood*
chemical_list: D002712:Chlorides; D017923:Sodium-Hydrogen Exchangers; D017693:Sodium Bicarbonate; D012964:Sodium