Specificity of Classical and Putative Cl- Transport Inhibitors on Membrane Transport Pathways in Human Erythrocytes

2003 ◽  
Vol 13 (4) ◽  
pp. 181-188 ◽  
Author(s):  
Steven Culliford ◽  
Clive Ellory ◽  
Hans-Jochen Lang ◽  
Heinrich Englert ◽  
Hery Staines ◽  
...  
Keyword(s):  
Membrane Transport ◽  
Human Erythrocytes ◽  
Transport Pathways ◽  
Transport Inhibitors

Electron transport pathways for the oxidation of endogenous substrate(s) in Acidithiobacillus ferrooxidans

2006 ◽  
Vol 52 (4) ◽  
pp. 317-327 ◽  
Author(s):  
Yongqiang Chen ◽  
Isamu Suzuki
Keyword(s):  
Electron Transport ◽  
Electron Acceptor ◽  
Acidithiobacillus Ferrooxidans ◽  
Complex I ◽  
Iron Chelators ◽  
Endogenous Respiration ◽  
Sugar Alcohols ◽  
Transport Pathways ◽  
Endogenous Substrate ◽  
Transport Inhibitors

Oxidation of endogenous substrate(s) of Acidithiobacillus ferrooxidans with O2 or Fe3+ as electron acceptor was studied in the presence of uncouplers and electron transport inhibitors. Endogenous substrate was oxidized with a respiratory quotient (CO2 produced/O2 consumed) of 1.0, indicating its carbohydrate nature. The oxidation was inhibited by complex I inhibitors (rotenone, amytal, and piericidin A) only partially, but piericidin A inhibited the oxidation with Fe3+ nearly completely. The oxidation was stimulated by uncouplers, and the stimulated activity was more sensitive to inhibition by complex I inhibitors. HQNO (2-heptyl-4-hydroxyquinoline N-oxide) also stimulated the oxidation, and the stimulated respiration was more sensitive to KCN inhibition than uncoupler stimulated respiration. Fructose, among 20 sugars and sugar alcohols including glucose and mannose, was oxidized with a CO2/O2 ratio of 1.0 by the organism. Iron chelators in general stimulated endogenous respiration, but some of them reduced Fe3+ chemically, introducing complications. The results are discussed in view of a branched electron transport system of the organism and its possible control.Key words: Acidithiobacillus ferrooxidans, endogenous respiration, uncouplers, electron transport.

Lithium fluxes in human erythrocytes

1979 ◽  
Vol 237 (1) ◽  
pp. C102-C110 ◽  
Author(s):  
B. E. Ehrlich ◽  
J. M. Diamond
Keyword(s):  
Significant Contribution ◽  
Temporal Variations ◽  
Depressive Illness ◽  
Human Erythrocytes ◽  
Transport Parameters ◽  
Manic Depressive Illness ◽  
Transport Pathways ◽  
Interindividual Variations ◽  
Manic Depressive

The contribution of four transport pathways to Li+ influx and efflux in human erythrocytes was determined quantitatively, using Li+ concentrations comparable to those found in vivo when Li+ is used as treatment for manic-depressive illness. All pathways were measured simultaneously on each subject's blood sample to avoid possible temporal variations in transport parameters. We found that Li+ efflux is 75% via countertransport and 25% via a leak. The bicarbonate-sensitive pathway accounts for 30% of influx while the remaining 70% is via a leak. The Na+-K+ pump makes no significant contribution to Li+ influx or efflux under physiological conditions. Li+ efflux for a given [Li+]i is 3–5 times the Li+ influx for the same [Li+]o. However, due to interindividual variations in Na+-Li+ counter-transport, Li+ efflux but not influx varies considerably among individuals.

Influence of importin α/β and exportin 1 on equine herpesvirus type 1 (EHV-1) replication in primary murine neurons

2013 ◽  
Vol 16 (4) ◽  
pp. 749-751 ◽  
Author(s):  
A. Słońska ◽  
J. Cymerys ◽  
J. Skwarska ◽  
A. Golke ◽  
M.W. Bańbura
Keyword(s):  
Equine Herpesvirus ◽  
Leptomycin B ◽  
Transport Pathways ◽  
Herpesvirus Type ◽  
Cytoplasmic Transport ◽  
Membrane Barrier ◽  
Importin Α ◽  
Equine Herpesvirus Type 1 ◽  
Transport Inhibitors

Abstract Viruses replicating in the nucleus need to cross the nuclear membrane barrier during infection, therefore disruption of specific nuclear transport pathways is crucial for their replication cycle. In the present study we have investigated the influence of nucleo-cytoplasmic transport inhibitors - ivermectin and leptomycin B, on EHV-1 replication in primary murine neurons. Obtained results suggest that the examined proteins - exportin 1 and importin α/β may participate, but are not required, during EHV-1 infection. Based on these results, it can be assumed that EHV-1 is able to use other receptors for nucleo-cytoplasmic transport.

scholarly journals Function Analysis of Choline Binding Domains of LytA, LytC and CbpD in The Biofilm Formation Process of Streptococcus Pneumoniae

2021 ◽  
Author(s):  
Hongsheng Ji ◽  
Yingshun Zhou ◽  
Luhua Zhang ◽  
Ying Wang ◽  
Feiyang Zhang ◽  
...  
Keyword(s):  
Membrane Transport ◽  
Biofilm Formation ◽  
Function Analysis ◽  
Amino Sugar ◽  
Extracellular Dna ◽  
Transport Pathways ◽  
Binding Domains ◽  
Phenotype Analysis ◽  
High Concentrations

Abstract Background: Choline binding proteins (CBPs) are a family of proteins that can interact with pneumococcal cell wall by choline binding domains (CBDs). In this study, we found a modified choline binding repeat (ChBp-I) with a pI of 7.66 can promote the development of biofilm in vitro. Thus, we aim to characterize the function of CBDs of LytA, LytC and CbpD in biofilm formation.Results: By transcriptome analysis, 81 genes were identified as down regulated and 138 genes were up regulated (|log2 fold change|≥1.5) under ChBp-I of 50mg/L. The up regulated genes are well clustered in membrane transport (carbohydrate, lipid, protein, cation and phosphate) and carbohydrate metabolism (fructose, mannose, galactose, starch, sucrose, amino sugar and nucleotide) related pathways. The up-regulated genes are mostly regulated the same under CBD-A, CBD-C and CBD-D. Phenotype analysis reveal high concentrations of CBD-C and CBD-D (>100μg/mL) but not CBD-A (negative charged) can promote the biofilm formation. Meanwhile, the existence of CBD-C and CBD-D promote the growth rate and both CBDs inhibit the autolysis of pneumococcal cell. By component analysis, these three CBDs were proved involved in the regulation of extracellular DNA, protein, cation and phosphate, and promote the forming of insoluble precipitates.Conclusions: The binding of CBPs can influence the membrane transport pathways and react with extracellular DNA and protein to promote biofilm formation in S. pneumoniae.

Separate entry pathways for phosphate and oxalate in rat brain microsomes

2000 ◽  
Vol 278 (6) ◽  
pp. C1183-C1190 ◽  
Author(s):  
X.-J. Meng ◽  
R. T. Timmer ◽  
R. B. Gunn ◽  
R. F. Abercrombie
Keyword(s):  
Rat Brain ◽  
Disulfonic Acid ◽  
Inhibitory Effects ◽  
Transport Pathways ◽  
Second Stage ◽  
Initial Stage ◽  
Ca Uptake ◽  
Brain Microsomes ◽  
Transport Inhibitors ◽  
Dependent Pathway

ATP-dependent 45Ca uptake in rat brain microsomes was measured in intracellular-like media containing different concentrations of PO4 and oxalate. In the absence of divalent anions, there was a transient 45Ca accumulation, lasting only a few minutes. Addition of PO4did not change the initial accumulation but added a second stage that increased with PO4 concentration. Accumulation during the second stage was inhibited by the following anion transport inhibitors: niflumic acid (50 μM), 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNDS; 250 μM), and DIDS (3–5 μM); accumulation during the initial stage was unaffected. Higher concentrations of DIDS (100 μM), however, inhibited the initial stage as well. Uptake was unaffected by 20 mM Na, an activator, or 1 mM arsenate, an inhibitor of Na-PO4cotransport. An oxalate-supported 45Ca uptake was larger, less sensitive to DIDS, and enhanced by the catalytic subunit of protein kinase A (40 U/ml). Combinations of PO4 and oxalate had activating and inhibitory effects that could be explained by PO4 inhibition of an oxalate-dependent pathway, but not vice versa. These results support the existence of separate transport pathways for oxalate and PO4 in brain endoplasmic reticulum.

Evidence against the Involvement of Mutarotase in the D-Glucose Uptake Activity of Isolated Human Erythrocyte Membranes

1972 ◽  
Vol 50 (9) ◽  
pp. 1028-1030 ◽  
Author(s):  
Arthur Kahlenberg ◽  
Gary Miller
Keyword(s):  
Glucose Uptake ◽  
Membrane Transport ◽  
Glucose Transport ◽  
Human Erythrocyte ◽  
Transport Process ◽  
Human Erythrocytes ◽  
Erythrocyte Membranes ◽  
Human Erythrocyte Membranes ◽  
Uptake Activity ◽  
Glucose Carrier

Mutarotase, the enzyme catalyzing the interconversion of the anomeric forms of D-glucose, has recently been suggested to be the membrane glucose carrier in human erythrocytes. However, hemoglobin-free human erythrocyte membranes possessing D-glucose uptake activity were found to be free of mutarotase activity. Mutarotase activity was detected in the membrane-free hemolysates of the cells. It is therefore concluded that the D-glucose uptake activity of isolated erythrocyte membranes is not due to the binding of the sugar to mutarotase, and that this enzyme is not involved in glucose transport in a manner compatible with most presently held concepts of the membrane transport process.

scholarly journals α- and β-Monosaccharide transport in human erythrocytes

2009 ◽  
Vol 296 (1) ◽  
pp. C151-C161 ◽  
Author(s):  
Jeffry M. Leitch ◽  
Anthony Carruthers
Keyword(s):  
Sugar Transport ◽  
Human Erythrocytes ◽  
Slow Phase ◽  
Sugar Uptake ◽  
Cell Water ◽  
Rapid Phase ◽  
Monosaccharide Transport ◽  
Equilibrium Exchange ◽  
Transport Inhibitors ◽  
Slow Transport

Equilibrative sugar uptake in human erythrocytes is characterized by a rapid phase, which equilibrates 66% of the cell water, and by a slow phase, which equilibrates 33% of the cell water. This behavior has been attributed to the preferential transport of β-sugars by erythrocytes (Leitch JM, Carruthers A. Am J Physiol Cell Physiol 292: C974–C986, 2007). The present study tests this hypothesis. The anomer theory requires that the relative compartment sizes of rapid and slow transport phases are determined by the proportions of β- and α-sugar in aqueous solution. This is observed with d-glucose and 3- O-methylglucose but not with 2-deoxy-d-glucose and d-mannose. The anomer hypothesis predicts that the slow transport phase, which represents α-sugar transport, is eliminated when anomerization is accelerated to generate the more rapidly transported β-sugar. Exogenous, intracellular mutarotase accelerates anomerization but has no effect on transport. The anomer hypothesis requires that transport inhibitors inhibit rapid and slow transport phases equally. This is observed with the endofacial site inhibitor cytochalasin B but not with the exofacial site inhibitors maltose or phloretin, which inhibit only the rapid phase. Direct measurement of α- and β-sugar uptake demonstrates that erythrocytes transport α- and β-sugars with equal avidity. These findings refute the hypothesis that erythrocytes preferentially transport β-sugars. We demonstrate that biphasic 3- O-methylglucose equilibrium exchange kinetics refute the simple carrier hypothesis for protein-mediated sugar transport but are compatible with a fixed-site transport mechanism regulated by intracellular ATP and cell shape.

scholarly journals Cyanidin 3-glucoside Is a Selective Inhibitor of Hepatic Bilirubin Uptake

2021 ◽  
Author(s):  
Paola Pelizzo ◽  
Marco Stebel ◽  
Nevenka Medic ◽  
Paola Sist ◽  
Andreja Vanzo ◽  
...  
Keyword(s):  
Membrane Transport ◽  
Protein Gene ◽  
Wistar Rat ◽  
Hepatic Uptake ◽  
Membrane Transporters ◽  
Basic Knowledge ◽  
Transport Pathways ◽  
Organ Specific ◽  
Rat Livers ◽  
Distinct Membrane

Abstract Background & Aims: One of the organ-specific functions of the liver is the excretion of bilirubin into the bile. Membrane transport of bilirubin from the blood to the liver is not only an orphan function, as there is no link to the protein/gene entities that carry it out, but also a poorly characterised function. The aim of this study was to investigate the pharmacology of bilirubin uptake in the liver of the female Wistar rat to improve basic knowledge in this neglected area of liver physiology.Methods: We treated isolated, perfused rat livers with repeated single-pass, albumin-free bilirubin boli. We monitored both bilirubin and bilirubin glucuronide in perfusion effluent with a biofluorometric assay. We tested the ability of nine molecules known to be substrates or inhibitors of sinusoidal membrane transporters to inhibit the hepatic uptake of bilirubin.Results: We found that cyanidin 3-glucoside and malvidin 3-glucoside are the only molecules that inhibit bilirubin uptake. These dietary anthocyanins resemble bromosulfophthalein (BSP), a substrate of several sinusoidal membrane transporters. The SLCO-specific substrates estradiol-17 beta-glucuronide, pravastatin, and taurocholate inhibited only bilirubin glucuronide uptake. Cyanidin 3-glucoside and taurocholate acted at physiological concentrations. The SLC22-specific substrates indomethacin and ketoprofen were inactive. We demonstrated the existence of a bilirubin glucuronide transporter that is inhibited by bilirubin, a fact reported only once in the literature.Conclusions: Data indicate that bilirubin and bilirubin glucuronide are transported into the liver via pharmacologically distinct membrane transport pathways. Some dietary anthocyanins may physiologically modulate the uptake of bilirubin into the liver.

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