scholarly journals UPHILL TRANSPORT INDUCED BY COUNTERFLOW

1957 ◽  
Vol 41 (2) ◽  
pp. 289-296 ◽  
Author(s):  
Thomas Rosenberg ◽  
W. Wilbrandt
Keyword(s):  
Transport System ◽  
Concentration Gradient ◽  
Flux Ratio ◽  
Mobile Carrier ◽  
Fixed Membrane ◽  
Feature Characteristic ◽  
Carrier Systems ◽  
Kinetic Treatment ◽  
Component Adsorption ◽  
Human Red Cells

1. In a membrane transport system containing a mobile carrier with affinities for two substrates a concentration gradient with respect to one of the substrates under certain conditions is able to induce an "uphill" transport (against the concentration gradient) of the other. 2. In a kinetic treatment quantitative conditions for such a "flow-induced uphill transport" and some of its characteristics are derived. 3. Experimentally the uphill transport of labelled glucose induced by a concentration gradient for mannose or unlabelled glucose is demonstrated in the human red cell. 4. It is shown that the flow-induced uphill transport is a feature characteristic for mobile carrier systems only and is not to be expected in systems in which the substrate is bound to a fixed membrane component ("adsorption membrane"), although such a system may yield identical transport kinetics. Also with respect to Ussing's flux ratio the two systems are different, the adsorption membrane meeting Ussing's criterion, the carrier membrane not. 5. It is concluded that the transport system in the human red cells must contain a mobile carrier, identical for glucose and mannose.

scholarly journals Kinetics and stoichiometry of Na-dependent Li transport in human red blood cells.

1978 ◽  
Vol 72 (2) ◽  
pp. 249-265 ◽  
Author(s):  
B Sarkadi ◽  
J K Alifimoff ◽  
R B Gunn ◽  
D C Tosteson
Keyword(s):  
Transport System ◽  
Red Cells ◽  
Normal Male ◽  
Red Cell ◽  
Red Cell Membrane ◽  
Human Red Blood Cells ◽  
Na Efflux ◽  
Tightly Coupled ◽  
Male Subjects ◽  
Human Red Cells

This paper describes the kinetics and stoichiometry of a tightly coupled Na-Li exchange transport system in human red cells. The system is inhibited by phloretin and furosemide but not by ouabain. Li influx by this system increases and saturates with increasing concentrations of external Li and internal Na and is inhibited competitively by external Na. Comparable functions relate Li efflux and Na efflux to internal and external Li and Na concentrations. Analysis of these relations yields the following values for the ion concentrations required to half-maximally activate the transport system: internal Na and Li 9.0 and 0.5 mM, respectively, external Na and Li 25 and 1.5 mM, respectively. The system performs a 1:1 exchange of Na and Li moving in opposite directions across the red cell membrane. We found no evidence for a simultaneous transport of more than one Na and Li by the system. The maximum transport rate of Na-dependent Li transport varied between 0.1 and 0.37 mmol/(liter of cells X h) in the red cells of the five normal male subjects studied. No significant variations between individual subjects were observed for bicarbonate-stimulated Li transport and for the residual Li fluxes which occur in the absence of bicarbonate and in the presence of ouabain plus phloretin.

scholarly journals Sinefungin shares AdoMet-uptake system to enter Leishmania donovani promastigotes

1995 ◽  
Vol 305 (1) ◽  
pp. 133-137 ◽  
Author(s):  
M A Phelouzat ◽  
M Basselin ◽  
F Lawrence ◽  
M Robert-Gero
Keyword(s):  
Cell Membrane ◽  
Concentration Gradient ◽  
Leishmania Donovani ◽  
Uptake System ◽  
Wild Type ◽  
Saturation Kinetics ◽  
Carrier Systems ◽  
Resistant Cells

The involvement of a carrier for sinefungin (SF) uptake in Leishmania donovani promastigotes is indicated by saturation kinetics, competition studies and SF accumulation against a 270-fold concentration gradient across the cell membrane. Whether SF uptake occurs via nucleoside- or AdoMet-carrier systems was investigated by competition experiments and comparison of the uptake of various molecules in wild-type and SF-resistant cells. Results show that SF did not inhibit purine or pyrimidine uptake whereas it competitively inhibited AdoMet uptake. Furthermore, the uptake of nucleosides in SF-resistant cells is similar to that in wild-type cells, whereas uptake of SF and AdoMet is lower.

Specificity of sugar transport by the intestine of the hamster

1960 ◽  
Vol 198 (1) ◽  
pp. 99-102 ◽  
Author(s):  
T. Hastings Wilson ◽  
Bernard R. Landau
Keyword(s):  
Small Intestine ◽  
Transport System ◽  
Concentration Gradient ◽  
Sugar Transport ◽  
Intestinal Wall ◽  
Sugar Derivatives

The specificity of the sugar transport system of the hamster small intestine was tested with 20 sugars and sugar derivatives not previously tested in this system. The absorption of sugars across the intestinal wall against a concentration gradient was tested with the everted sac technique in vitro. 3-Deoxyglucose, 4-0-methylgalactose, 6-deoxy-6-fluoroglucose and α-methylglucoside were transported while a variety of other sugars were not. From the data derived from the study of a total of 49 sugars tested in this system, certain generalizations are made as to the structural limitations of the sugar-absorbing capacity of the hamster intestine.

Transport of l-tyrosine by the small intestine in vitro

1960 ◽  
Vol 199 (1) ◽  
pp. 127-130 ◽  
Author(s):  
Edmund C. C. Lin ◽  
T. Hastings Wilson
Keyword(s):  
Small Intestine ◽  
Amino Acid ◽  
Transport System ◽  
Concentration Gradient ◽  
Animal Species

l-Tyrosine was absorbed against a concentration gradient by sacs of isolated small intestine obtained from several animal species. During absorption the tissue segments accumulated the amino acid to concentrations as high as nine times that in the suspending medium. In the case of the hamster the rate of transport was maximal in the mid portion of the small intestine. Studies on specificity of the transport system showed that l-tyrosine and dl-meta-tyrosine were transported while no activity was observed with d-tyrosine, dl-ortho-tyrosine, and 3,5-diiodo-l-tyrosine. Transport of l-tyrosine was inhibited by l-phenylalanine and l-methionine but not by d-phenylalanine. High tyrosine diet did not alter the rate of the in vitro transport of this amino acid in the rat.

Transport of salicylate in proximal tubule (S2 segment) isolated from rabbit kidney

1988 ◽  
Vol 254 (4) ◽  
pp. F554-F561
Author(s):  
L. Schild ◽  
F. Roch-Ramel
Keyword(s):  
Proximal Tubule ◽  
Transport System ◽  
Concentration Gradient ◽  
Bath Temperature ◽  
Rabbit Kidney ◽  
Luminal Membrane ◽  
Carrier Mediated Transport ◽  
Secretory Transport ◽  
Luminal Ph

The secretory and reabsorptive transport of salicylate was studied in the isolated and perfused rabbit proximal tubule (S2 segment). Salicylate secretion (Jb----lsal) fulfilled the criteria for a carrier-mediated transport system: Jb----lsal was saturable, was reversibly inhibited by probenecid, and occurred against a concentration gradient. The Km and Vmax for this secretory transport were 80 microM and 3,200 fmol.min-1.mm-1, respectively. At luminal pH of 7.4 and 6.6, salicylate reabsorption (Jl----bsal) was low (100 fmol.min-1.mm-1). Jl----bsal was stimulated by increasing the bath PCO2 or by removing basolateral HCO3-; Jl----bsal was inhibited by ethoxyzolamide and by SITS in the bath. Our results indicate that salicylate reabsorption depends on H+ secretion, consistent with reabsorption by simple nonionic diffusion. When salicylate was present in the lumen only, Jl----bsal increased after inhibition of the secretory transport by adding ouabain or probenecid in the bath or by lowering the bath temperature. These results are compatible with luminal recycling of salicylate, and suggest the presence of a mediated secretory transporter located at the luminal membrane.

scholarly journals Kinetika dan mekanisme sistem transpor Cd(II) antar fasa melalui teknik membran cair fasa ruah dengan oksin sebagai zat pembawa

2015 ◽  
Vol 1 (1) ◽  
pp. 97
Author(s):  
Zaharasmi Kahar ◽  
Djufri Mustafa ◽  
Wiwit
Keyword(s):  
Transport System ◽  
Liquid Membrane ◽  
Chloroform Solution ◽  
Bulk Liquid ◽  
Bulk Liquid Membrane ◽  
First Order ◽  
Mobile Carrier ◽  
Membrane Technique ◽  
Model Curve ◽  
Good Agreement

 ABSTRACT The transport and separation of Cd(II) through  bulk liquid membrane technique had been investigated and optimised. Cd(II) was transported  through a liquid membrane  of  chloroform solution containing oxine as mobile carrier and  received by EDTA in stripping phase. In compliance with optimum condition, the flux of Cd(II) crossing the membrane was studied, and applied further into a model of the transport system and kinetics mechanism. Concentration of Cd(II) in feed  and stripping phases were experimentally determined, and monitored by the atomic absorption spectrophotometer at lmaks 228.8 nm.  The model curve of time dependence of Cd(II) reduced concentrations in the feed, membrane and  stripping phases show good agreement and characterized as a transport system for Cd(II) interphase involved two consecutive irreversible first order reactions. The rate constant of transport at temperature 28°C are k1 0.0416 minutes-1, k2 0.0354  minutes-1 and  activation energy  32.96 kJ mol-1

scholarly journals Active transport of GSSG from reconstituted erythrocyte ghosts

Blood ◽  
1975 ◽  
Vol 46 (1) ◽  
pp. 111-117 ◽  
Author(s):  
J Prchal ◽  
SK Srivastava ◽  
E Beutler
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Concentration Gradient ◽  
Human Erythrocyte ◽  
Red Cells ◽  
Intracellular Concentration ◽  
Maximal Velocity ◽  
Erythrocyte Ghosts ◽  
The Relationship

Abstract Human erythrocyte ghosts were loaded with 35S-labeled GSSG and with a sucrose marker, and the transport of GSSG to the suspending medium was studied. GSSG transport from ghosts occurred only when ATP was also present in the ghosts, proceeded against a concentration gradient, and was inhibited by fluoride. The rate of transport was dependent upon the intracellular concentration of GSSG. The relationship between GSSG concentration and rate of transport was sigmoidal. Half-maximal transport was observed at a GSSG concentration of approximately 9.6mM. The maximal velocity was estimated to be in the range of 0.27 umole GSSG per ml of ghosts per hr. These data suggest that the rate of GSSG transport a physiologic concentrations of GSSG is not sufficiently rapid to account for the turnover of glutathione by red cells. It seems more likely that the GSSG transport system serves an emergency function of erythrocytes.

scholarly journals Some Kinetic and Metabolic Characteristics of Calcium-Induced Potassium Transport in Human Red Cells

1972 ◽  
Vol 60 (4) ◽  
pp. 406-429 ◽  
Author(s):  
Floyd M. Kregenow ◽  
Joseph F. Hoffman
Keyword(s):  
Flux Ratio ◽  
Iodoacetic Acid ◽  
Cell System ◽  
Na Transport ◽  
Metabolic Characteristics ◽  
Substrate Removal ◽  
Maximum Value ◽  
Metabolic Dependence ◽  
K Permeability ◽  
Human Red Cells

When fresh human erythrocytes or their ghosts are incubated with Ca + IAA (iodoacetic acid) + adenosine, K permeability increases; K permeability also increases when energy-depleted cells or their ghosts are incubated with Ca alone. Na transport decreases or remains unaltered in both situations. The Ca-induced increase in K permeability in the depleted cell system is qualitatively similar to that seen in the fresh cell system and furnishes a means for studying the metabolic dependence of calcium's action. Studies with the depleted system suggest that the normal refractiveness of the cell to calcium is provided by a metabolically dependent substrate. Removal of this substrate allows Ca to enter the cell and exert its effect. By using 47Ca, a maximum value was obtained (3–7 x 10-6 moles/liter of red blood cells) for the quantity of calcium that is taken up by the cell and responsible for the change in K permeability. Measurements of the unidirectional fluxes of K, obtained during the time Ca increases K permeability, appear to satisfy the flux ratio equation for passive diffusion through a membrane.

Monosaccharide transport into hemocytes of a sipunculan worm Themiste dyscrita

1985 ◽  
Vol 249 (1) ◽  
pp. R139-R144
Author(s):  
R. L. Ingermann ◽  
R. E. Hall ◽  
J. M. Bissonnette ◽  
R. C. Terwilliger
Keyword(s):  
Transport System ◽  
Concentration Gradient ◽  
Blood Cells ◽  
Cytochalasin B ◽  
Potent Inhibitor ◽  
Simple Diffusion ◽  
Initial Concentration ◽  
Half Saturation Constant ◽  
Monosaccharide Transport ◽  
Saturation Kinetics

The hemerythrin-containing blood cells, or hemocytes, of the sipunculan worm Themiste dyscrita were found to have a stereospecific and nonconcentrative monosaccharide transport system. The transport system transferred both D-glucose and 3-O-methyl-D-glucose (3-OMG), and transport into cells by this system was rapid, reaching 50% equilibrium in approximately 20 s at 10 degrees C with an initial concentration gradient of 0.1 mM; the contribution to total uptake by simple diffusion was very small. 3-OMG uptake showed saturation kinetics with a low half-saturation constant (Km less than or equal to 0.1 mM). The uptake of labeled 3-OMG by the hemocytes was strongly inhibited by unlabeled 3-OMG, 2-deoxy-D-glucose, alpha- and beta-D-glucose, D-galactose, and D-mannose. It was moderately inhibited by D-xylose, only slightly by alpha-methyl-D-glucoside and D-fructose, and uninhibited by sucrose, L-glucose, or D-sorbitol. Phloretin was more potent than phloridzin in blocking entry of 3-OMG. Cytochalasin B did not bind tightly to the T. dyscrita transporter and was not a potent inhibitor of transport; it half-maximally inhibited 3-OMG transport at 0.1 mM. Therefore, despite some differences the data suggest functional similarities in the mechanism of monosaccharide transport into blood cells of mammals and this invertebrate.

scholarly journals Identification of a Mobile Carrier-mediated Sugar Transport System in Muscle

1964 ◽  
Vol 239 (2) ◽  
pp. 369-374 ◽  
Author(s):  
H.E. Morgan ◽  
D.M. Regen ◽  
C.R. Park
Keyword(s):  
Transport System ◽  
Sugar Transport ◽  
Mobile Carrier
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