title: Hemodialysis and red cell cation transport in uremia: role of membrane free fatty acids.
abstract: Active and facilitated cation transport in erythrocytes of uremic patients may be improved acutely by hemodialysis, although the mechanisms remain unknown. As nonesterified fatty acids (NEFA) can affect Na+ pump activity in vitro, changes in plasma and red cell membrane NEFA content following a single hemodialysis procedure were examined and compared with acute changes in erythrocyte cation flux rates in 34 hemodialysis patients. In nonsodium-loaded cells, small changes in Na+ pump flux with dialysis did correlate with changes in intracellular Na+ content (r = 0.59; N = 17; P less than 0.01). On average, neither maximal Na+ pump activity nor Na+/Li+ counter-transport flux improved with dialysis, but Na+/K+/Cl- cotransport rates rose 25% post-dialysis (P less than 0.02). Plasma NEFA levels rose 87% following hemodialysis but erythrocyte membrane NEFA content declined by 23% (P less than 0.001). Importantly, 24 of the 34 subjects studied had a decrease in erythrocyte membrane NEFA content of greater than 10%, and in these patients, the fall in membrane NEFA correlated with an increase in ouabain-sensitive Na+ efflux (r = 0.564; P less than 0.01). The effects of hemodialysis on both erythrocyte NEFA content and Na+ pump flux could be reproduced by incubating pre-dialysis cells in fatty acid-free albumin. We conclude that acute changes in membrane NEFA may modulate active cation transport in uremic erythrocytes.
authors.affiliation: Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts.
authors.forename: R A
authors.initials: RA
authors.lastname: Kelly
authors.forename: M L
authors.initials: ML
authors.lastname: Canessa
authors.forename: T I
authors.initials: TI
authors.lastname: Steinman
authors.forename: W E
authors.initials: WE
authors.lastname: Mitch
mesh_terms: D000368:Aged; D001693:Biological Transport, Active; D004910:Erythrocyte Membrane / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism*; D008875:Middle Aged; D015221:Potassium Channels / Q000378:metabolism*; D006435:Renal Dialysis; D015222:Sodium Channels / Q000378:metabolism*; D014511:Uremia / Q000378:metabolism*
chemical_list: D005230:Fatty Acids, Nonesterified; D008563:Membrane Lipids; D015221:Potassium Channels; D015222:Sodium Channels