title: Uridine transport in human erythrocytes: data from normal subjects and from patients with renal failure.
abstract: Erythrocyte uridine transport has been studied in eight normal individuals and eight patients on haemodialysis for chronic renal failure. The initial rate of zero-trans uridine influx at 37 degrees C has been measured as a function of extracellular uridine concentration using [14C]-labelled uridine. The results are consistent with Michaelis-Menten kinetics. In normal humans the mean Vmax for uridine influx was 32.8 +/- 6.4 mumol (1 cells)-1 s-1 (mean +/- S.D.) and the mean Km was 190 +/- 12.3 microM. The measurements made in renal failure patients were not significantly different (mean Vmax 30.1 +/- 7.1 mumol (1 cells)-1 s-1, mean Km, 185 +/- 13.2 microM). These results are discussed with reference to the reported data on uridine transport in human erythrocytes at temperatures between 4 and 35 degrees C; it is suggested that zero-trans uridine influx shows a decrease in temperature dependence above 25 degrees C. The Vmax for zero-trans uridine influx at 37 degrees C in normal erythrocytes represents a turnover number for the nucleoside transporter of 180 uridine molecules per second.
authors.affiliation: Renal Unit, Churchill Hospital, Headington, Oxford.
authors.forename: F C
authors.initials: FC
authors.lastname: Fervenza
authors.forename: D
authors.initials: D
authors.lastname: Meredith
authors.forename: J C
authors.initials: JC
authors.lastname: Ellory
authors.forename: B M
authors.initials: BM
authors.lastname: Hendry
mesh_terms: D000328:Adult; D000368:Aged; D001693:Biological Transport, Active; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007676:Kidney Failure, Chronic / Q000097:blood*; D007700:Kinetics; D008875:Middle Aged; D012016:Reference Values; D014529:Uridine / Q000097:blood*
chemical_list: D014529:Uridine