Involvement of NO in the Endothelium-Independent Relaxing Effects of Nω-Hydroxy-l-arginine and Other Compounds Bearing a C=NOH Function in the Rat Aorta
- Petr Vetrovsky1,3,
- Jean-Luc Boucher2,
- Christa Schott1,
- Petra Beranova1,3,
- Karel Chalupsky1,3,
- Noëlle Callizot1,
- Bernard Muller1,
- Gustav Entlicher3,
- Daniel Mansuy2 and
- Jean-Claude Stoclet1
- 1Pharmacology and Physico-Chemistry, Centre National de la Recherche Scientifique (Unité Mixte Recherche 7034) and University Louis Pasteur, Strasbourg, France (P.V., C.S., P.B., K.C., N.C., B.M., J.-C.S.); 2Laboratory of Pharmacological and Toxicological Chemistry and Biochemistry, Centre National de la Recherche Scientifique (UnitéMixte Recherche 8601) and University René Descartes, Paris, France (J.L.B., D.M.); and 3Department of Biochemistry, Charles University, Prague, Czech Republic (P.V., P.B., K.C., G.E.)
- Jean-Claude Stoclet, Pharmacologie et Physico-Chimie, Université Louis Pasteur, Faculté de Pharmacie, BP 24, F-67401 Illkirch Cedex, France. E-mail:stoclet{at}aspirine.u-strasbg.fr
Abstract
The mechanisms of vasorelaxation elicited byNω-hydroxy-l-arginine (l-NOHA) and other compounds bearing a C=NOH function and the structural determinants governing this effect were investigated in rat aorta. l-NOHA, formamidoxime, five aromatic monosubstituted amidoximes, and one aromatic monosubstituted ketoxime elicited relaxation in endothelium-denuded rings.N-Hydroxyguanidine and substitutedN-hydroxyguanidines were markedly less active. Relaxations induced by l-NOHA and by the most active studied compound, 4-chlorobenzamidoxime (ClBZA), were unmodified by the presence of endothelium. In endothelium-denuded rings, they were blunted by the NO scavenger 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (300 μM) and by the inhibitor of guanylyl-cyclase activation 1H[1,2,4,]oxadiazolo[4,3-a]quinoxalin-1-one (1 μM). In addition, l-NOHA- and ClBZA both caused cGMP accumulation. l-Arginine, but notd-arginine (1 mM), antagonized the effect ofl-NOHA but not ClBZA. Both l-NOHA- and ClBZA-induced relaxations were inhibited by the NAD(P)H-dependent enzymes inhibitor diphenyliodonium (30 μM) and the NAD(P)H-dependent reductases inhibitor 7-ethoxyresorufin (10 μM), but they were unmodified by the cytochrome P450 (P450) inhibitor proadifen (10 μM) and by the NO synthase inhibitorNω-nitro-l-arginine methyl ester (l-NAME, 300 μM). These results show thatl-NOHA and other compounds with a C=NOH function can cause endothelium-independent relaxation in the rat aorta. They suggest that activation of guanylyl cyclase and NO formation is implicated in relaxation and that a 7-ethoxyresorufin-sensitive NAD(P)H-dependent pathway is involved. On one hand, l-NOHA and amidoximes may be useful tools for characterizing this pathway in blood vessels and, on the other, may offer a novel approach for treating vascular diseases with impaired endothelial NO activity.
Footnotes
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This investigation was partially supported by Barrande Grant 00967ZD. P.V., P.B., and K.C. were the recipients of fellowships provided by the French Embassy in Prague.
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Primary laboratory of origin: Pharmacology and Physico-Chemistry, Centre National de la Recherche Scientifique (Unité Mixte Recherche 7034) and University Louis Pasteur (Strasbourg, France).
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DOI: 10.1124/jpet.102.038612
- Abbreviations:
- l-NOHA
- Nω-hydroxy-l-arginine
- P450
- cytochrome P450
- PTIO
- 2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide
- ODQ
- 1H[1,2,4,]oxadiazolo[4,3-a]quinoxalin-1-one
- l-NAME
- Nω-nitro-l-arginine methyl ester
- IBMX
- isobutylmethylxanthine
- ClBZA
- 4-chlorobenzamidoxime
- NO2BZA
- 4-nitrobenzamidoxime
- HXBZA
- 4-n-(hexyloxy)benzamidoxime
- MXBZA
- 4-methoxybenzamidoxime
- ClBK
- 4-chloroacetophenone oxime
- DMSO
- dimethyl sulfoxide
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- Received May 15, 2002.
- Accepted July 17, 2002.
- The American Society for Pharmacology and Experimental Therapeutics
