Cytokine treatment increases arginine metabolism and uptake in bovine pulmonary arterial endothelial cells.
L-Arginine (L-Arg) is metabolized to nitric oxide (NO) by NO synthase (NOS) or to urea by arginase (AR). L-Arg is transported into bovine pulmonary arterial endothelial cells (BPAECs) by cationic amino acid transporter-2 (CAT-2). We hypothesized that cytokine treatment would increase L-Arg metabolism and increase CAT-2 mRNA expression. BPAECs were incubated for 24 h in medium (control) or medium with lipopolysaccharide and tumor necrosis factor-alpha (L-T). L-T increased nitrite production (3.1 +/- 0.4 nmol/24 h vs. 1.8 +/- 0.1 nmol/24 h for control; P < 0.01) and urea production (83.5 +/- 29.5 nmol/24 h vs. 17.8 +/- 8.6 nmol/24 h for control; P < 0.05). L-T-treated BPAECs had greater endothelial and inducible NOS mRNA expression compared with control cells. Increasing the medium L-Arg concentration resulted in increased nitrite and urea production in both the control and the L-T-treated BPAECs. L-T treatment resulted in measurable CAT-2 mRNA. L-T increased L-[(3)H]Arg uptake (5.78 +/- 0.41 pmol vs. 4.45 +/- 0.10 pmol for control; P < 0.05). In summary, L-T treatment increased L-Arg metabolism to both NO and urea in BPAECs and resulted in increased levels of CAT-2 mRNA. This suggests that induction of NOS and/or AR is linked to induction of CAT-2 in BPAECs and may represent a mechanism for maintaining L-Arg availability to NOS and/or AR.
Nelin
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LD
Vascular Physiology Group and Department of Pediatrics, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, USA. lnelin@salud.unm.edu
Nash
H E
HE
Chicoine
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LG
D000818:Animals; D001120:Arginine / Q000378:metabolism* / Q000494:pharmacology; D027202:Cationic Amino Acid Transporter 2 / Q000235:genetics / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D009585:Nitrogen Dioxide / Q000378:metabolism; D011651:Pulmonary Artery / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D014508:Urea / Q000378:metabolism
D027202:Cationic Amino Acid Transporter 2; D008070:Lipopolysaccharides; D009573:Nitrites; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D014508:Urea; D001120:Arginine; D019001:Nitric Oxide Synthase; D009585:Nitrogen Dioxide