A simple and convenient cell model for the characterization of volume sensitive taurine and GABA transport.
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Animals↗
Biomedical subjects
D A Fincham
Publications and source records attributed to D A Fincham.
Characterization of a novel Na+-independent amino acid transporter in horse erythrocytes.
Horse erythrocytes are polymorphic with respect to L-alanine permeability. The present investigation compared the specificity, kinetics and cation-dependence of erythrocyte amino acid transport in two groups of thoroughbred horses, those with erythrocyte L-alanine permeabilities in the range 5-15 mumol/h per litre of cells (0.2 mM extracellular L-alanine, 37 degrees C) (transport-negative type) and those with L-alanine permeabilities in the range 450-700 mumol/h per litre of cells (transport-positive type). Transport-positive cells are shown to possess a novel high-affinity, stereospecific, Na+-independent transporter selective for neutral amino acids of intermediate size. This carrier system (provisional designation asc) operates preferentially in an exchange mode and is functionally absent from erythrocytes of transport-negative-type horses.
Alanine↗
Breed and species comparison of amino acid transport variation in equine erythrocytes.
The amino acid permeability of red blood cells from Equus caballus (thoroughbred, Arab, shire and pony), E przewalskii (Przewalski's horse), E asinus (donkey and mule) and E burchelli (common or plains zebra) was measured. Individual animals exhibited stable but widely differing rates of L-[U-14C]alanine uptake in the range 5 to 1554 mumol (litre cells)-1 h-1 (0.2 mM extracellular L-alanine, 37 degrees C). Of the thoroughbreds tested, 30 per cent had red blood cells which were essentially impermeable to L-alanine (5 to 10 mumol (litre cells)-1 h-1, giving transport rates similar to those found previously in amino acid transport-deficient sheep erythrocytes. In contrast, only 3 per cent of the ponies tested had red blood cells impermeable to L-alanine. No cases of erythrocyte amino acid transport deficiency were found in the other horse breeds and species tested.
Alanine↗
Red cell amino acid transport. Evidence for the presence of system Gly in guinea pig reticulocytes.
Guinea pig reticulocytes are shown to possess an Na+-dependent glycine transporter which also requires Cl- for activity. Glycine transport by this route is saturable (apparent Km 98 microM; Vmax 24 mumol/g Hb per h) and inhibited by sarcosine. The properties of this carrier closely resemble those of System Gly previously demonstrated in pigeon and human erythrocytes. In contrast, no System Gly activity was detected in mature guinea pig erythrocytes.
Animals↗
Nucleoside transport in human erythrocytes. Nitrobenzylthioinosine binding and uridine transport activities have similar radiation target sizes.
Intact human erythrocytes were irradiated in the frozen state with a high-energy electron beam. Nitrobenzylthioinosine-sensitive uridine influx, equilibrium exchange uridine influx and high-affinity nitrobenzylthioinosine binding were inactivated as a simple exponential function of the radiation dose, indicating an in situ target size of 122 000. The results suggest that the nitrobenzylthioinosine-binding site(s) and the permeation site(s) of the transporter are present on the same transporter element.
Biological Transport↗