Abstract
Our objective was to determine whether hydroxylamine is a possible intermediate in the oxidative conversion of L-arginine to nitric oxide. Vasorelaxation by hydroxylamine is known to be mediated by nitric oxide. The vasorelaxant properties of hydroxylamine were examined using rat aortic rings and an isolated rat lung perfusion model. Hydroxylamine and acetylcholine were equally effective in relaxing norepinephrine-contracted intact aortic rings, whereas only hydroxylamine relaxed aortic rings with endothelium removed. This endothelium-independent vasorelaxation by hydroxylamine indicated that the hydroxylamine-converting enzyme is not localized solely within endothelial cells. Catalase, an enzyme known to oxidize hydroxylamine to nitric oxide, was present in homogenates of intact and endothelium-denuded rings. Cyanamide, another catalase substrate and a known precursor of nitroxyl (HNO), was not a vasorelaxant of aortic rings or of isolated, hypoxia-constricted lungs. These results suggest that free nitroxyl is not an intermediate in the oxidation of hydroxylamine to nitric oxide. An overall pathway for the oxidative conversion of L-arginine through an hydroxylamine intermediate to nitric oxide is proposed.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 527-533 |
| Number of pages | 7 |
| Journal | Biochemical and Biophysical Research Communications |
| Volume | 163 |
| Issue number | 1 |
| DOIs | |
| State | Published - Aug 30 1989 |
Bibliographical note
Funding Information:ACKNOWLEDGMENTS --This work was supported by the Veterans Administration. We thank Karen Coffee and Daniel P. Nelson for carrying out the experimental part of this study. The authors also wish to thank Prof. Herbert T. Nagasawaf or valuable discussions.