A Na(+)-dependent system A and ASC-independent amino acid transport system stimulated by glucagon in rat hepatocytes.
The effects of glucagon on amino acid transport in rat hepatocytes are not fully understood. We examined the effect of this hormone on alanine, serine and cysteine preferring system (system ASC)-mediated amino acid transport in rat hepatocyte monolayers using 2-aminoisobutyric acid (AIB) and l -cysteine. Glucagon induced a time and protein synthesis-dependent stimulation of Na(+)-dependent alanine preferring system (system A)-independent AIB transport. The glucagon-induced increase in transport activity was not modified by substrate starvation and not related to changes in the intracellular pool of amino acids. Glucagon did not modify system ASC activity measured by l -cysteine. Therefore the transport activity of AIB independent of system A stimulated by glucagon cannot be attributed to system ASC. This suggests a Na(+)-dependent transport system in rat hepatocytes not identified until now.
Lim
S K
SK
Laboratoire de Biochimie A Hôpital Saint-Antoine (AP-HP), 184, rue du Faubourg Saint-Antoine, 75571 Paris Cedex 12, France.
Cynober
L
L
De Bandt
J P
JP
Aussel
C
C
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D005934:Glucagon / Q000494:pharmacology*; D008099:Liver / Q000378:metabolism*; D008297:Male; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism
D000596:Amino Acids; D011500:Protein Synthesis Inhibitors; D005934:Glucagon; D012964:Sodium