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Exogenous N G ‐hydroxy‐ l ‐arginine causes nitrite production in vascular smooth muscle cells in the absence of nitric oxide synthase activity
Author(s) -
Schott C.A.,
Bogen C.M.,
Vetrovsky P.,
Berton C.C.,
Stoclet J.C.
Publication year - 1994
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(94)80457-5
Subject(s) - nitric oxide , chemistry , arginine , nitrite , nitric oxide synthase , vascular smooth muscle , biochemistry , atp synthase , smooth muscle , enzyme , biology , amino acid , endocrinology , nitrate , organic chemistry
Nitric oxide (NO) production from exogenous N G ‐hydroxy‐ l ‐arginine (OH‐ l ‐Arg) was investigated in rat aortic smooth muscle cells in culture by measuring nitrite accumulation in the culture medium. As well, the interaction between OH‐ l ‐Arg and l ‐arginine uptake via the y + cationic amino acid transporter was studied. In cells without NO‐synthase activity, OH‐ l ‐Arg (1–1000 μM) induced a dose‐dependent nitrite production with a half‐maximal effective concentration (EC 50 ) of 18.0 ± 1.5 μM ( n = 4–7). This nitrite accumulation was not inhibited by the NO‐synthase inhibitor N G ‐nitro‐ l ‐arginine methyl ester, l ‐NAME (300 μM). In contrast, it was abolished by miconazole (100 μM), an inhibitor of cytochrome P 450 . Incubation of vascular smooth muscle cells with LPS (10 ) induced an l‐name inhibited nitrite accumulation, but did not enhance the OH‐ l ‐Arg induced nitrite production. OH‐ l ‐Arg and other cationic amino acids, L‐lysine and l ‐ornithine, competitively inhibited [ 3 H]‐ l ‐arginine uptake m rat aortic smooth muscle cells, with inhibition constants of 195 ± 23 μM( n = 12), 260 ± 40 μM( n = 5) and 330 ± 10 μM( n = 5), respectively. These results show that OH‐ l ‐Arg is recognized by the cationic l ‐amino acid carrier present in vascular smooth muscle cells and can be oxidized to NO and nitrite in these cells in the absence of NO‐synthase, probably by cytochrome P 450 or by a reaction involving a cytochrome P 450 byproduct.