2-2--(hydroxynitrosohydrazono)bis-ethanamine and 1-1-diethyl-2-hydroxy-2-nitrosohydrazine

Topics: Alkenes; Catalysis; Cobalt; Hydrazines; Kinetics; Magnetic Resonance Spectroscopy; Nitric Oxide Donors; Nitrogen Oxides; Nitroso Compounds; Spectrophotometry, Ultraviolet; Vitamin B 12

Nitric oxide (NO) is an important regulator of angiogenesis and neovascularization. The nature of endothelial cell motility responses to NO was examined using a Boyden chamber method. NO generated via decomposition of either DEA/NO or DETA/NO produced increases in human umbilical vein endothelial cell (HUVEC) chemotaxis, which were completely abrogated by ODQ, a soluble guanylyl cyclase inhibitor. Measurements of NO either directly by chemiluminescence or its chemistry with diaminofluorescein revealed that chemotaxis was driven by subtle NO gradients between the lower and the upper wells in this system. In addition to diffusion and volatilization from the upper chambers, the data showed that HUVEC consumption of NO contributed to these sustained gradients. Comparison of DEA/NO- and DETA/NO-mediated responses suggested that the persistence of spatial NO gradients is as significant as the absolute magnitude of NO exposure per unit time. The findings suggest that subnanomolar NO gradients are sufficient to mobilize endothelial cell migration into hypoxic tissue during neovascularization events, such as in wound healing and cancer.

Topics: Cell Movement; Cells, Cultured; Chemotaxis; Diffusion; Endothelial Cells; Endothelium, Vascular; Guanylate Cyclase; Humans; Hydrazines; Neovascularization, Physiologic; Nitric Oxide; Nitrogen Oxides; Oxadiazoles; Quinoxalines; Triazenes; Volatilization

1. The effects of the nitric oxide (NO) donors S-nitroso-N-acetylpenicillamine (SNAP), sodium(Z)-1-(N,N-diethylamino)diazen-1-ium-1,2-diolate (DEA-NONOate), and (Z)-1-[N-(2-Aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA-NONOate) on force of contraction (F(c)) were studied in atrial and ventricular muscle strips obtained from wild-type (WT) and myoglobin-deficient (myo(-/-)) mice. 2. SNAP slightly reduced F(c) in preparations from WT mice at concentrations above 100 microM; this effect was more pronounced in myo(-/-) mice. 3. DEA-NONOate reduced F(c) in preparations from myo(-/-) mice to a larger extent than those from WT mice. 4. DETA-NONOate reduced F(c) in preparations from myo(-/-) but not from WT mice. 5. Pre-incubation with an inhibitor of the soluble guanylyl cyclase (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; 100 microM) prevented the effects of SNAP, DEA-NONOate and DETA-NONOate on F(c) in myo(-/-) mice. 6. It is suggested that, in physiological conditions, myoglobin acts as intracellular scavenger preventing NO from reaching its intracellular receptors in cardiomyocytes, whereas, in myoglobin-deficient conditions, NO is able to reduce contractility via activation of the soluble guanylyl cyclase/cyclic GMP pathway.

Topics: Animals; Electric Stimulation; Enzyme Inhibitors; Female; Hydrazines; In Vitro Techniques; Male; Mice; Myocardial Contraction; Myocardium; Myoglobin; Nitric Oxide Donors; Nitrogen Oxides; Nitroso Compounds; Oxadiazoles; Quinoxalines; S-Nitroso-N-Acetylpenicillamine

We found that several nitric oxide donors had similar potency in killing mature and immature forms of oligodendrocytes (OLs). Because of the possibility of interaction of nitric oxide with intracellular thiols, we tested the effect of the nitrosonium ion donor S-nitrosylglutathione (SNOG) in OL cultures in the setting of cystine deprivation, which has been shown to cause intracellular glutathione depletion. Surprisingly, the presence of 200 microM SNOG completely protected OLs against the toxicity of cystine depletion. This protection appeared to be due to nitric oxide, because it could be blocked by hemoglobin and potentiated by inclusion of superoxide dismutase. We tested the effect of three additional NO* donors and found that protection was not seen with diethylamine NONOate, a donor with a half-life measured in minutes, but was seen with dipropylenetriamine NONOate and diethylaminetriamine NONOate, donors with half-lives measured in hours. This need for donors with longer half-lives for the protective effect suggested that NO* was required when intracellular thiol concentrations were falling, a process evolving over hours in medium depleted of cystine. These studies suggest a novel protective role for nitric oxide in oxidative stress injury and raise the possibility that intracerebral nitric oxide production might be a mechanism of defense against oxidative stress injury in OLs.

Topics: Animals; Apoptosis; Catalase; Cell Survival; Cells, Cultured; Cellular Senescence; Cerebral Cortex; Cysteine; Free Radicals; Glutathione; Guanylate Cyclase; Hemoglobins; Hydrazines; Mutagens; Neuroprotective Agents; Nitric Oxide; Nitric Oxide Donors; Nitrogen Oxides; Nitroso Compounds; Oligodendroglia; Oxidation-Reduction; Oxidative Stress; Rats; Rats, Sprague-Dawley; S-Nitrosoglutathione; Signal Transduction; Superoxide Dismutase