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Regulation of L‐arginine transport and nitric oxide release in superfused porcine aortic endothelial cells.
Author(s) -
Bogle R G,
Baydoun A R,
Pearson J D,
Mann G E
Publication year - 1996
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1996.sp021138
Subject(s) - arginine , nitric oxide , extracellular , bradykinin , chemistry , biochemistry , medicine , endocrinology , amino acid , biology , receptor
1. We have investigated whether changes in extracellular ion composition and substrate deprivation modulate basal and/or bradykinin‐stimulated L‐arginine transport and release of nitric oxide (NO) and prostacyclin (PGI2) in porcine aortic endothelial cells cultured and superfused on microcarriers. 2. Saturable L‐arginine transport (Km = 0.14 +/‐ 0.03 mM; Vmax = 2.08 +/‐ 0.54 nmol min‐1 (5 x 10(6) cells)‐1) was pH insensitive and unaffected following removal of extracellular Na+ or Ca2+. 3. Cationic arginine analogues, including L‐lysine and L‐ornithine, inhibited L‐arginine transport, whilst 2‐methylaminoisobutyric acid, beta‐2‐amino‐bicyclo[2,2.1]‐heptane‐2‐carboxylic acid, L‐phenylalanine, 6‐diazo‐5‐oxo‐norleucine, L‐glutamine, L‐cysteine and L‐glutamate were poor inhibitors. 4. Deprivation of L‐arginine (30 min to 24 h) reduced intracellular free L‐arginine levels from 0.87 +/‐ 0.07 to 0.40 +/‐ 0.05 mM (P < 0.05) and resulted in a 40% stimulation of L‐arginine, L‐lysine and L‐ornithine transport. 5. L‐arginine and NG‐monomethyl‐L‐arginine (L‐NMMA), but not N omega‐nitro‐L‐arginine methyl ester (L‐NAME), trans‐stimulated efflux of L‐[3H]arginine. 6. Depolarization of endothelial cells with 70 mM K+ reduced L‐arginine influx and prevented the stimulation of transport by 100 nM bradykinin, but agonist‐induced release of NO and PGI2 was still detectable. 7. Basal rates of L‐arginine transport and NO release were unaffected during superfusion of cells with a nominally Ca(2+)‐free solution. Bradykinin‐stimulated L‐arginine transport was insensitive to removal of Ca2+, whereas agonist‐induced NO release was abolished. 8. Although bradykinin‐stimulated NO release does not appear to be coupled directly to the transient increase in L‐arginine transport, elevated rates of L‐arginine influx via system y+ in response to agonist‐induced membrane hyperpolarization or substrate deprivation provide a mechanism for enhanced L‐arginine supply to sustain NO generation.