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Up‐regulation of system A activity in the regenerating rat liver
Author(s) -
Martinez-Mas Joan-Vicenç,
Ruiz-Montasell Bonaventura,
Felipe Antonio,
Casado Javier,
Pastor-Anglada Marçal
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80219-k
Subject(s) - vesicle , alanine , chemistry , biophysics , liver regeneration , transmembrane protein , amino acid , biochemistry , mediated transport , hepatocyte , membrane transport , biology , membrane , microbiology and biotechnology , in vitro , regeneration (biology) , receptor
System A activity for neutral amino acid transport, measured as the MeAIB‐sensitive Na + ‐dependent l ‐alanine uptake, is induced 6 h after partial hepatectomy in plasma membrane vesicles from rat livers. Other Na + ‐dependent transporters, like system ASC (MeAIB‐insensitive Na + ‐dependent l ‐alanine transport) and the nucleoside carrier show similar inductions. Up‐regulation of system A is not explained by changes in the dissipation rate of the Na + transmembrane gradient, as deduced from uptake measurements performed in the presence of monensin. To determine whether induced system A shared any similarity with the activity found in hepatoma cell lines, we analyzed the N ‐ethylmaleimide (NEM) sensitivity of system A in both regenerating and control rat liver plasma membrane vesicles. NEM treatment was equally effective in inhibiting system A in both experimental groups. Thus, during the prereplicative phase of liver growth, a transport activity similar to basal system A is up‐regulated in liver parenchymal cells, by a stable mechanism that does not involve changes in the Na + transmembrane gradient.