Inactivation of amino acid transport in rat hepatocytes and hepatoma cells by PCMBS

1988 ◽  
Vol 255 (3) ◽  
pp. C340-C345 ◽  
Author(s):  
T. C. Chiles ◽  
K. L. Dudeck-Collart ◽  
M. S. Kilberg
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Rat Hepatocytes ◽  
Cell Types ◽  
Hepatoma Cells ◽  
Transport Systems ◽  
Acid Transport ◽  
System A ◽  
System L ◽  
Normal Rat

the transport of amino acids by both normal rat hepatocytes and rat H4 hepatoma cells has been tested for inactivation by sulfhydryl-preferring, protein-modifying reagents. Amino acid transport by systems A, ASC, N, L, and y+ in the H4 hepatoma cells was relatively resistant to inactivation by the alkylating reagent N-ethylmaleimide (NEM), whereas uptake mediated by systems A, ASC, and L was decreased in normal rat hepatocytes. In contrast, nearly all of the amino acid transport systems in both cell types were inhibited strongly by p-chloromercuribenzene sulfonate (PCMBS). The exceptions were the H4 hepatoma system y+ activity (72% of control) and system L-mediated uptake (121% of control) in normal hepatocytes. Although transport via system A was equally sensitive to inhibition by PCMBS in both cell types, substrate-dependent protection from this inactivation was observed only in the H4 hepatoma cells. These results illustrate the significant differences that exist between normal and transformed liver cells in respect to amino acid transport inactivation by sulfhydryl reagents.

scholarly journals A rapid method for the functional reconstitution of amino acid transport systems from rat liver plasma membranes. Partial purification of System A

1988 ◽  
Vol 255 (3) ◽  
pp. 963-969 ◽  
Author(s):  
A R Quesada ◽  
J D McGivan
Keyword(s):  
Amino Acid ◽  
Rapid Method ◽  
Amino Acid Transport ◽  
Plasma Membranes ◽  
Transport Systems ◽  
Partial Purification ◽  
Acid Transport ◽  
Transport Activity ◽  
System A ◽  
System L

A rapid method for the functional reconstruction of amino acid transport from liver plasma-membrane vesicles using the neutral detergent decanoyl-N-glucamide (‘MEGA-10’) is described. The method is a modification of that previously employed in this laboratory for reconstitution of amino acid transport systems from kidney brush-border membranes [Lynch & McGivan (1987) Biochem. J. 244, 503-508]. The transport activities termed ‘System A’, ‘System N’, and ‘System L’ are all reconstituted. The reconstitution procedure is rapid and efficient and is suitable as an assay for transport activity in studies involving membrane fractionation. By using this reconstitution procedure, System A transport activity was partially purified by lectin-affinity chromatography.

scholarly journals Adenosine induces system A amino acid transport in rat hepatocytes

1990 ◽  
Vol 52 ◽  
pp. 118
Author(s):  
Hiroaki Kiyokawa ◽  
Hiroyuki Fukui ◽  
Hiroyuki Mizuguchi ◽  
Akiharu Kubo ◽  
Norio Kono ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Rat Hepatocytes ◽  
Acid Transport ◽  
System A

scholarly journals Expression of the surface antigen 4F2hc affects system-L-like neutral-amino-acid-transport activity in mammalian cells

1997 ◽  
Vol 324 (2) ◽  
pp. 535-541 ◽  
Author(s):  
Stefan BRÖER ◽  
Angelika BRÖER ◽  
Bernd HAMPRECHT
Keyword(s):  
Amino Acid ◽  
Surface Antigen ◽  
Amino Acid Transport ◽  
Cho Cells ◽  
Mammalian Cells ◽  
Primary Cultures ◽  
Transport Systems ◽  
Acid Transport ◽  
Transport Activity ◽  
System L

Mammalian cells possess a variety of amino acid-transport systems with overlapping substrate specificity. System L is one of the major amino acid-transport systems of non-epithelial cells. By expression cloning we have recently demonstrated that the surface antigen 4F2hc (CD98) is a necessary component for expression of system-L-like amino acid-transport activity in C6-BU-1 rat glioma cells [Bröer, Bröer and Hamprecht (1995) Biochem. J. 312, 863–870]. 4F2hc mRNA was detected in CHO cells, COS cells, activated lymphocytes isolated from mouse spleen and primary cultures of astrocytes. In all these cell types, Na+-independent isoleucine transport was mediated by system L. No contribution of system y+L to isoleucine or arginine transport was detected in C6-BU-1 cells. In lymphocytes, both system-L-like amino acid-transport activity and 4F2hc mRNA levels increased after treatment with phorbol ester plus ionomycin. Antisense oligonucleotides caused modest inhibition of Na+-independent isoleucine transport in C6-BU-1 cells and primary cultures of astroglial cells, whereas arginine transport was unaffected. Overexpression of 4F2hc cDNA in CHO cells resulted in an increase in Na+-independent isoleucine transport.

scholarly journals Reduction of In Vivo Placental Amino Acid Transport Precedes the Development of Intrauterine Growth Restriction in the Non-Human Primate

Nutrients ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 2892
Author(s):  
Fredrick J. Rosario ◽  
Anita Kramer ◽  
Cun Li ◽  
Henry L. Galan ◽  
Theresa L. Powell ◽  
...  
Keyword(s):  
Amino Acid ◽  
Amino Acid Transport ◽  
Intrauterine Growth Restriction ◽  
Growth Restriction ◽  
Acid Transport ◽  
Mole Percent ◽  
System A ◽  
System L ◽  
Human Primate

Intrauterine growth restriction (IUGR) is associated with reduced placental amino acid transport (AAT). However, it remains to be established if changes in AAT contribute to restricted fetal growth. We hypothesized that reduced in vivo placental AAT precedes the development of IUGR in baboons with maternal nutrient restriction (MNR). Baboons were fed either a control (ad libitum) or MNR diet (70% of control diet) from gestational day (GD) 30. At GD 140, in vivo transplacental AA transport was measured by infusing nine (13)C- or (2)H-labeled essential amino acids (EAAs) as a bolus into the maternal circulation at cesarean section. A fetal vein-to-maternal artery mole percent excess ratio for each EAA was measured. Microvillous plasma membrane (MVM) system A and system L transport activity were determined. Fetal and placental weights were not significantly different between MNR and control. In vivo, the fetal vein-to-maternal artery mole percent excess ratio was significantly decreased for tryptophan in MNR. MVM system A and system L activity was markedly reduced in MNR. Reduction of in vivo placental amino acid transport precedes fetal growth restriction in the non-human primate, suggesting that reduced placental amino acid transfer may contribute to IUGR.

scholarly journals Membrane potential of rat hepatoma cells in culture: Influence of factors affecting amino acid transport

1995 ◽  
Vol 15 (4) ◽  
pp. 173-184 ◽  
Author(s):  
M. F. Mouat ◽  
A. C. Cantrell ◽  
K. L. Manchester
Keyword(s):  
Membrane Potential ◽  
Amino Acid ◽  
Amino Acid Transport ◽  
Rat Hepatocytes ◽  
Hepatoma Cells ◽  
Acid Transport ◽  
Factors Affecting ◽  
Cells In Culture ◽  
Rat Hepatoma ◽  
Rat Hepatoma Cells

The effect has been studied of various media, hormones and of amino acids on the membrane potential of rat hepatoma cells in culture measured by microelectrode impalement. Cells in Eagle's minimal essential medium plus 5% serum had a value which varied daily from about 5–8 mV, inside negative. The membrane potential of rat hepatocytes was measured to be 8.7 ± 0.2mV, inside negative. The membrane potential of the hepatoma cells was decreased by insulin and increased by glucagon. Membrane potential was unaffected by change of medium to Hanks' or Earle's balanced salt solutions or deprivation of serum. It was, however, reduced in cells in phosphate-buffered saline and by reduction of pH. The former effect was shown to be due to the higher [Na+] of phosphat-buffered saline as opposed to the other media. Addition of alanine, glycine, serine, proline and methylaminoisobutyrate all reduced membrane potential by 2–3 mV. Smaller decreases were seen with methionine, leucine and phenylalanine, but none with glutamine, threonine, BCH (2-aminonorborane-2-carboxylic acid) and D-alanine. The results are compared with the effects of similar conditions on aminoisobutyrate uptake. Whilst there was a correlation under some conditions there was not under others. It is concluded that for the hepatoma cells factors additional to the membrane potential must exert some influence on the capacity for amino acid transport.

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