Homocysteine uptake by human umbilical vein endothelial cells in culture.
The characteristics of the uptake of L-homocysteine by cultures of human umbilical vein endothelial cells have been examined. Uptake occurred by Na(+)-dependent and Na(+)-independent systems, but was essentially independent of the pH of the uptake medium. The Na(+)-independent system corresponded to system L, being totally inhibited by the presence of beta-2-aminobicyclo(2,2,1)heptane-2-carboxylic acid (BCH) a system L analogue. It was concluded on the basis of starvation experiments coupled with failure to detect any inhibition in the presence of 2-methylaminoisobutyric acid (MeAIB), a system A analogue, that the Na(+)-dependent uptake was wholly accounted for by system ASC. The kinetic properties of systems L and ASC were determined by omitting Na+ from the uptake medium and incorporating BCH in the medium, respectively. It has been concluded on the basis of the inhibitory effects of a number of amino acids that uptake of homocysteine occurs by those systems which transport cysteine.
Department of Biochemistry, University of Wales College of Cardiff, U.K.
M J
MJ
Ewadh
N
N
Tudball
F A
FA
Rose
D000596:Amino Acids / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D003545:Cysteine / Q000378:metabolism; D004730:Endothelium, Vascular / Q000378:metabolism*; D006710:Homocysteine / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D012964:Sodium / Q000502:physiology
D000596:Amino Acids; D006710:Homocysteine; D012964:Sodium; D003545:Cysteine