title: Nitric oxide exposure and sulfhydryl modulation alter L-arginine transport in cultured pulmonary artery endothelial cells.
abstract: The effect of nitric oxide (NO) exposure and sulfhydryl-reactive chemicals on L-arginine transport in pulmonary artery endothelial cells was evaluated. Exposure of pulmonary artery endothelial cells to 7.5 ppm (0.4 microM) NO for 4 h resulted in a significant (p < 0.05) reduction of Na(+)-dependent but not Na(+)-independent L-arginine transport. More prolonged exposure for 12-24 h reduced both Na(+)-dependent and Na(+)-independent transport of L-arginine with maximal loss of transport after 18 h of exposure (p < 0.02 for both). Similarly, incubation of cells in the presence of 50-200 microM S-nitroso-acetyl-penicillamine (SNAP) (but not 500 microM each of nitrate or nitrite) for 2 h also reduced both the Na(+)-dependent and Na(+)-independent transport of L-arginine (p < 0.05 for all concentrations). The SNAP-induced reduction of L-arginine transport was blocked by the NO scavenger oxyhemoglobin. When cell monolayers were exposed to varying concentrations of the sulfhydryl reactive chemicals N-ethylmaleimide (NEM) and acrolein, a dose-dependent reduction of L-arginine transport by both Na(+)-dependent and Na(+)-independent processes was observed. Na(+)-dependent L-arginine transport was more susceptible to inhibition by exposure to NO and to sulfhydryl reactive chemicals. Incubation of cells with 0.5 mM of the thiol-containing agent N-acetyl-L-cysteine prior to and during NEM or acrolein exposure blocked NEM and acrolein-induced reduction of L-arginine transport by both Na(+)-dependent and Na(+)-independent processes. Similarly, NO-induced reductions of Na(+)-dependent and Na(+)-independent L-arginine transport were reversed to control levels 24 h after termination of NO exposure. Treatment with the disulfide reducing agent dithiothreitol after exposure to NO resulted in partial reversal of the decreases in L-arginine transport. These results demonstrate that exposure to exogenous NO is responsible for reversible reductions of plasma membrane-dependent L-arginine transport mediated by both the Na(+)-dependent (system Bo,+) and the Na(+)-independent (system y+) transport processes. Modulation of the sulfhydryl status of plasma membrane proteins involved in L-arginine transport, such as L-arginine transporters and/or Na+/K(+)-ATPase, may be responsible, at least in part, for reductions in overall L-arginine transport in pulmonary artery endothelial cells.
authors.affiliation: Medical Research Service, Veterans Affairs Medical Center, Gainesville, FL 32608-1197, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Patel
authors.forename: A J
authors.initials: AJ
authors.lastname: Abeles
authors.forename: E R
authors.initials: ER
authors.lastname: Block
mesh_terms: D000111:Acetylcysteine / Q000494:pharmacology; D000171:Acrolein / Q000037:antagonists & inhibitors / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D004229:Dithiothreitol / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005033:Ethylmaleimide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D009566:Nitrates / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D009573:Nitrites / Q000494:pharmacology; D010396:Penicillamine / Q000031:analogs & derivatives / Q000494:pharmacology; D011651:Pulmonary Artery / Q000378:metabolism; D026423:S-Nitroso-N-Acetylpenicillamine; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013552:Swine
chemical_list: D009566:Nitrates; D009573:Nitrites; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D000171:Acrolein; D026423:S-Nitroso-N-Acetylpenicillamine; D001120:Arginine; D007770:L-Lactate Dehydrogenase; D010396:Penicillamine; D005033:Ethylmaleimide; D004229:Dithiothreitol; D000111:Acetylcysteine