Transport of 2-aminoisobutyric acid in cultured endothelial cells.
Conflicting reports exist concerning the presence of a Na(+)-coupled amino acid transport system in cultured endothelial cells. We have employed a non-metabolizable analog, 2-aminoisobutyric acid (AIB), to investigate the activity of Na(+)-dependent amino acid transport in cultured human umbilical vein endothelial cells (HUVEC). We found a pronounced saturable, Na(+)-dependent component of AIB uptake in 'fresh' (non-starved) HUVEC. The Na(+)-dependent component accounted for 78% of total AIB uptake with a high sensitivity to external Na+. The accumulation of AIB was inhibited by ouabain preincubation, consistent with the energetics of Na(+)-coupled transport. Amiloride, an epithelial Na+ channel blocker, also inhibited AIB transport at high concentration. The results strongly support the presence of a Na(+)-coupled transport system of amino acid in HUVEC.
Lau
Y T
YT
Department of Physiology, Chang Gung College of Medicine and Technology, Taiwan.
Chen
J K
JK
Chen
B S
BS
Hsieh
C C
CC
D000584:Amiloride / Q000494:pharmacology; D000621:Aminoisobutyric Acids / Q000378:metabolism*; D001692:Biological Transport; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D010042:Ouabain / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology
D000621:Aminoisobutyric Acids; D002250:Carbon Radioisotopes; C100049:2-aminoisobutyric acid; D012965:Sodium Chloride; D010042:Ouabain; D000584:Amiloride