title: L-arginine transport and nitric oxide synthesis in human endothelial progenitor cells.
abstract: Nitric oxide (NO) is an endogenous vasodilator molecule synthetized from L-arginine by a family of nitric oxide synthases. In differentiated human endothelial cells, it is well known that L-arginine uptake via cationic amino acid transporters (y(+)/CAT) or system y(+)L is required for the NO synthesis via endothelial nitric oxide synthase, but there are no reports in human endothelial progenitor cell (hEPC). Therefore, we isolated hEPCs from peripheral blood of healthy donors and cultured them for either 3 (hEPC-3d) or 14 days (hEPC-14d) to characterize the L-arginine transport and NO synthesis in those cells. L-arginine transport and NO synthesis were analyzed in the presence or absence of N-ethylmaleimide or L-nitroarginine methyl ester, as inhibitors of y(+)/CAT system and nitric oxide synthases, respectively. The results showed that L-arginine uptake is higher in hEPC-14d than in hEPC-3d. Kinetic parameters for L-arginine transport showed the existence of at least 2 transporter systems in hEPC: a high affinity transporter system (K(m)= 4.8 ± 1.1 μM for hEPC-3d and 6.1 ± 2.4 μM for hEPC-14d) and a medium affinity transporter system (K(m) = 85.1 ± 4.0 μM for hEPC-3d and 95.1 ± 8 μM for hEPC-14d). Accordingly, hEPC expressed mRNA and protein for CAT-1 (ie, system y(+)) and mRNA for 2 subunits of y(+)L system, yLAT1, and 4F2hc. Higher L-citruline production and NO bioavailability (4-fold), and endothelial nitric oxide synthase expression (both mRNA and protein) were observed in hEPC-14d compared with hEPC-3d. Finally, the high L-citruline formation observed in hEPC-14d was blocked by N-ethylmaleimide. In conclusion, this study allowed to identity a functional L-arginine/NO pathway in two hEPC differentiation stages, which improves the understanding of the physiology of these precursor cells.
authors.affiliation: Department of Clinical Biochemistry and Immunology, Faculty of Pharmacy, University of Concepción, Concepcion, Chile.
authors.forename: Francisca
authors.initials: F
authors.lastname: Díaz-Pérez
authors.forename: Claudia
authors.initials: C
authors.lastname: Radojkovic
authors.forename: Valeria
authors.initials: V
authors.lastname: Aguilera
authors.forename: Carlos
authors.initials: C
authors.lastname: Veas
authors.forename: Marcelo
authors.initials: M
authors.lastname: González
authors.forename: Liliana
authors.initials: L
authors.lastname: Lamperti
authors.forename: Carlos
authors.initials: C
authors.lastname: Escudero
authors.forename: Claudio
authors.initials: C
authors.lastname: Aguayo
mesh_terms: D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism*; D001692:Biological Transport; D027201:Cationic Amino Acid Transporter 1 / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007700:Kinetics; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis*; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D013234:Stem Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*
chemical_list: D027201:Cationic Amino Acid Transporter 1; D012333:RNA, Messenger; C420825:SLC7A1 protein, human; D009569:Nitric Oxide; D001120:Arginine; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D005033:Ethylmaleimide; D019331:NG-Nitroarginine Methyl Ester