ABSTRACT
The activity of the urea transporter was determined in human erythrocytes of the Kidd blood type Jk(a-b-) by measuring unidirectional urea and thiourea fluxes in tracer flux experiments and urea net fluxes in light-scattering experiments. When compared with control cells, Jk(a-b-) cells exhibited diminished urea and thiourea fluxes and lacked the kinetic characteristics of mediated transport, suggesting that in these cells urea and thiourea moved only by simple diffusion through the lipid bilayer. Control experiments showed that anion, water, and ethylene glycol permeabilities were the same in Jk(a-b-) and control cells. These experiments thus demonstrate that Jk(a-b-) cells lack mediated urea transport and strongly support the notion that urea transport function is separate from the transport for anions, water, and ethylene glycol, probably because different proteins are responsible for these transport functions.
Subject(s)
Erythrocytes/physiology , Kidd Blood-Group System/genetics , Urea/blood , Biological Transport , Erythrocytes/drug effects , Humans , Kinetics , Reference Values , Thiourea/blood , Urea/pharmacologyABSTRACT
The lytic properties of red cells from Jk(a+,b+), Jk(a-, b+) and Jk(a+b-) (normal), Jk(a-b-), and obligate Jk heterozygotes were studied. The Jk(a-b-) cells did not hemolyze for at least 15 minutes in either 2 M urea or methylurea, whereas normal cells were completely hemolyzed in 2 minutes. Red cells from Jk heterozygotes demonstrated intermediate levels of hemolysis when compared to normal and Jk(a-b-) red cells. In addition, these cells had less than 10 percent hemolysis when suspended in 2 M methylurea prepared in 0.4 percent phosphate-buffered saline (pH 7.2). This method may be an alternative to hemagglutination titration scoring for the detection of Jk, especially in paternity cases.
Subject(s)
Blood Group Antigens/genetics , Genetic Carrier Screening , Kidd Blood-Group System/genetics , Alcohols , Calcium Channel Agonists , Detergents , Genetic Carrier Screening/methods , Hemagglutination Tests , Hemolysis/drug effects , Humans , Kidd Blood-Group System/immunology , Paternity , Phospholipases , UreaABSTRACT
The phenomenon of red cell lysis in urea was investigated for both normal and Jk(a-b-) red cells. Using 14C urea, urea was shown to be transported across the membrane in both cell types. In normal cells this resulted in an influx of water, cell swelling and complete lysis within 2 min. However, in Jk(a-b-) red cells, the presence of urea above 300 mM slowed water movement and delayed hemolysis for at least 15 min. Similar effects could be induced by pretreating normal red cells with p-chloromercuribenzene sulfonate (PCMBS) or by raising the pH of the urea solution to 8.0.
Subject(s)
Cell Membrane Permeability , Erythrocyte Membrane/physiology , Erythrocytes/pathology , Urea/pharmacokinetics , HumansABSTRACT
Dia occurs with a frequency of 8.2 to 14.7 percent in Mexican-Americans living in three Texas communities. Of 4225 blood samples tested, only six (0.14%) were Di(a+b-), and none of 2540 samples was Di(a-b-). In other studies, 1 of 525 random white blood donors was Di(a+), and Dib was well developed in 100 random umbilical cord blood samples.
