Nitric Oxide Research

Nitric oxide is an extremely important and versatile messenger in the biological system. At first, it was recognized as an endothelium-derived relaxing factor in the vascular system. It has also been identified as a neurotransmitter or neuromodurator in the neuronal system and a cytotoxic factor in the immune system.  Also, it is believed to be related to some tissue damage such as ischemia/reperfusion tissue damage and excitatory neuronal death.

Products

NO Detection  - NO2/NO3 Assay kit  / other reagents for NO Detection

NO Donor - NOCs  / NORs  / Nitrosothiols  /  Caged NO  /  Peroxynitrite Donor

NO Detection

NO2/NO3 Assay Kit-C II (Colorimetric) ~ Griess Reagent Kit ~

NO2/NO3 Assay Kit-F II (Fluorometric) ~ 2,3-Diaminonaphtalene Kit ~

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Other Reagents for NO Detedction

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NO Donors

NOCs

NOCs are stable NO-amine complexes that spontaneously release NO, without cofactors, under physiological conditions. The rate of NO release depends on the chemical structure of NOC. The mechanism of spontaneous NO generation by NOCs is very simple compared to other classical NO donors, such as nitroglycerin and nitropurusside, and the by-products do not interfere with cell activities. A single NOC molecule releases two NO molecules (as indicated in the reaction scheme); the release rate of the second NO molecule is very slow. NOCs can be used to add controlled amounts of pure NO to experimental systems at controlled rates with minimal side effects. The amount of NO released can be easily manipulated by altering the concentration and selection of NOC reagents. Dojindo offers four different NOCs (NOC 5, 7, 12 and 18) with different half-lifes. Stock solutions of NOC prepared in alkaline solutions, such as aqueous NaOH, are relatively stable. However,the NOC stock solution should be used within one day because it degrades about 5% per day, even at -20 ºC. The release of NO begins immediately after adding the stock solution to a sample solution.

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  NORs

NORs are ideal NO donors with completely different chemical structures from the other NO donors. Although NORs do not have any ONO₂ or ONO moiety, they spontaneously release NO at a steady rate. It is also confirmed that the by-products do not possess any significant bioactivities even though the NO release mechanism of NOR has not been completely determined. NOR 3, isolated from Streptomyces genseosporeus, is reported to have strong vasodilatory effects on rat and rabbit aortas, and dog coronary arteries. Its activity (ED₅₀=1 nM) is 300 times that of isosorbide dinitrate (ISDN). NOR 3 also increases the plasma cyclic GMP levels, whereas ISDN does not. NOR is a potent inhibitor of platelet aggregation and thrombus formation. NOR 3 (IC₅₀=0-7 mM) effectively inhibits 100% of ADP-initiated human platelet aggregation; whereas ISDN inhibits only 32% of the total aggregation, even at 100 mM concentrations. NOR 3 has also been reported to have antianginal and cardioprotective effects in the ischemia/reperfusion system. In the rat methacholin induced coronary vasospasm model, NOR 3 suppressed the elevation of the ST segment dose-dependently and significantly at 1 mg/kg. On the other hand, ISDN suppressed it significantly at 3.2 mg/kg. The difference in the NO release rate of NOR reagents was reflected even on the in vivo hypotensive effects. NOR may also be used orally in a 0.5% methylcellulose suspension. NOR is relatively stable in DMSO solution. NOR 1, which has the shortest half-life, is a promising reagent for making NO standard solutions for calibration. For the preparation of the standard solution, a precisely diluted NOR 1/DMSO solution is added to the buffer solutions.

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    Nitrosothiols

SNAP is a stable N-nitrosothiol commonly used as an NO donor. Nitrosothiol compounds release NO and become disulfides under specific physiological conditions. The rate of NO release by SNAP is not clear because there are many factors influencing NO production from SNAP, including light, heat, metal ions (Fe²⁺, Cu²⁺, Cu⁺, Hg²⁺), cell membrane components, and so on. While most of the S-nitrosothiol compounds are unstable, SNAP and S-Nitrosoglutathione are exceptionally stable.S-Nitrosoglutathione is also water-soluble. SNAP, instead of S-Nitrosoglutathione, should be used to add S-nitrosothiols in experimental systems with NO. Although S-nitrosothiol is a good NO donor with no nitrate tolerance, there is evidence that S-nitrosothiol itself has NO-like activity during guanylate cyclase activation. Another important reaction of nitrosothiol is NO transfer to other thiol compounds. Since it depends on the pKa of thiols, this transfer reaction proceeds at physiological pH levels. The relaxation efficiency of these nitrosothiol has been compared using rat aorta ring samples: SNAP > S-Nitrosoglutathione = S-Nitroso-N-acetylcysteine > S-NitrosocoenzymeA > S-Nitroso-L-cysteine. Dr. Kowaluk and others reported that the spontaneous liberation of NO from SNAP could not account for in vitro vascular relaxation. The spontaneous release of NO from nitrosothiol compounds may not be a key element of vascular relaxation. Metabolites of nitrosothiol generated at the cell membrane might be the essential element for relaxation.

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    Caged NO

BNN 3, BNN 5 Na and BNN 5 methyl ester are photolabile NO donors, also known as ?aged NO· They have absorption maxima around 300 nm for the release of NO upon the irradiation of 300-360 nm wavelength with a xenon lamp or laser flash light. Each BNN molecule releases two molecules of NO. The quantum yield of the BNN reaction and the rate of NO release are high: Complete NO release occurs within 20 msec of irradiation. Two radicals are generated in the BNN molecule after NO is released, but they are immediately reconjugated inside the molecule. BNN 3 and BNN 5 methyl ester are soluble in DMSO (>5 mM) and ethanol; BNN 5 Na is soluble in aqueous solutions. Stock solutions of BNN 3 and BNN 5 Na are stable over two months at -30 ºC. However, BNN 5 methyl ester in DMSO solution is only stable for two weeks at -30 ºC.

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    Peroxynitrite Donors - SIN-1

SIN-1, a metabolite of the vasodilator molsidomine, is utilized to separately estimate the effectiveness of NO and peroxynitrite with other NO donors. SIN-1 spontaneously decomposes in the presence of molecular oxygen to generate NO and superoxide (as indicated in the figure above). Both products bind very rapidly to form peroxynitrite (rate constant k: 3.7x10^-7 M^-1s^-1). Therefore, SIN-1 is a useful compound that generates peroxynitrite in an efficient manner. Peroxynitrite is a very strong oxidant that generates a hydroxyl and nitrosyldioxyl radicals under physiological conditions. Peroxynitrite also decomposes to generate nitrate ion quickly in the acidic conditions and slowly in basic conditions. Those species have a different bioactivity from NO.

Product Code : S264-10 ( 25mg )

                         S264-12 ( 100mg )                   

Storage : -20 ºC

Shipping Condition : Blue or Dry Ice

Price :  inqure

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