Effects of pyrogallol, hydroquinone and duroquinone on responses to nitrergic nerve stimulation and NO in the rat anococcygeus muscle. 1999

M La, and M J Rand
Department of Medical Laboratory Science, Royal Melbourne Institute of Technology, Australia.

1. The hypothesis that endogenous superoxide dismutase (SOD) protects the nitrergic transmitter from inactivation by superoxide and that this explains the lack of sensitivity of the transmitter to superoxide generators was tested in the rat isolated anococcygeus muscle. 2. Responses to nitrergic nerve stimulation or to NO were not significantly affected by exogenous SOD or by the Cu/Zn SOD inhibitor diethyldithiocarbamic acid (DETCA). 3. Hydroquinone produced a concentration-dependent reduction of responses to NO with an IC50 of 27 microM, and higher concentrations reduced relaxant responses to nitrergic nerve stimulation with an IC50 of 612 microM. The effects of hydroquinone were only slightly reversed by SOD, so it does not appear to be acting as a superoxide generator. 4. Pyrogallol produced a concentration-dependent reduction in responses to NO with an IC50 value of 39 microM and this effect was reversed by SOD (100-1000 u ml(-1)). Pyrogallol did not affect responses to nitrergic nerve stimulation. Treatment with DETCA did not alter the differentiating action of pyrogallol. 5. Duroquinone produced a concentration-dependent reduction of relaxations to NO with an IC50 value of 240 microM and 100 microM slightly decreased nitrergic relaxations. After treatment with DETCA, duroquinone produced greater reductions of relaxant responses to NO and to nitrergic stimulation, the IC50 values being 8.5 microM for NO and 40 microM for nitrergic nerve stimulation: these reductions were reversed by SOD. 6. The findings do not support the hypothesis that the presence of Cu/Zn SOD explains the greater susceptibility of NO than the nitrergic transmitter to the superoxide generator pyrogallol, but suggest that it may play a role in the effects of duroquinone.

UI MeSH Term Description Entries
D008297 Male Males
D009126 Muscle Relaxation That phase of a muscle twitch during which a muscle returns to a resting position. Muscle Relaxations,Relaxation, Muscle,Relaxations, Muscle
D009130 Muscle, Smooth Unstriated and unstriped muscle, one of the muscles of the internal organs, blood vessels, hair follicles, etc. Contractile elements are elongated, usually spindle-shaped cells with centrally located nuclei. Smooth muscle fibers are bound together into sheets or bundles by reticular fibers and frequently elastic nets are also abundant. (From Stedman, 25th ed) Muscle, Involuntary,Smooth Muscle,Involuntary Muscle,Involuntary Muscles,Muscles, Involuntary,Muscles, Smooth,Smooth Muscles
D009569 Nitric Oxide A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP. Endogenous Nitrate Vasodilator,Mononitrogen Monoxide,Nitric Oxide, Endothelium-Derived,Nitrogen Monoxide,Endothelium-Derived Nitric Oxide,Monoxide, Mononitrogen,Monoxide, Nitrogen,Nitrate Vasodilator, Endogenous,Nitric Oxide, Endothelium Derived,Oxide, Nitric,Vasodilator, Endogenous Nitrate
D009930 Organic Chemicals A broad class of substances containing carbon and its derivatives. Many of these chemicals will frequently contain hydrogen with or without oxygen, nitrogen, sulfur, phosphorus, and other elements. They exist in either carbon chain or carbon ring form. Organic Chemical,Chemical, Organic,Chemicals, Organic
D011748 Pyrogallol A trihydroxybenzene or dihydroxy phenol that can be prepared by heating GALLIC ACID. 1,2,3-Trihydroxybenzene,Pyrogallic acid,acid, Pyrogallic
D002614 Chelating Agents Chemicals that bind to and remove ions from solutions. Many chelating agents function through the formation of COORDINATION COMPLEXES with METALS. Chelating Agent,Chelator,Complexons,Metal Antagonists,Chelators,Metal Chelating Agents,Agent, Chelating,Agents, Chelating,Agents, Metal Chelating,Antagonists, Metal,Chelating Agents, Metal
D004050 Ditiocarb A chelating agent that has been used to mobilize toxic metals from the tissues of humans and experimental animals. It is the main metabolite of DISULFIRAM. Diethyldithiocarbamate,Diethylcarbamodithioic Acid,Diethyldithiocarbamic Acid,Dithiocarb,Ditiocarb Sodium,Ditiocarb, Ammonium Salt,Ditiocarb, Bismuth Salt,Ditiocarb, Lead Salt,Ditiocarb, Potassium Salt,Ditiocarb, Sodium Salt,Ditiocarb, Sodium Salt, Trihydrate,Ditiocarb, Tin(4+) Salt,Ditiocarb, Zinc Salt,Imuthiol,Sodium Diethyldithiocarbamate,Thiocarb,Zinc Diethyldithiocarbamate,Ammonium Salt Ditiocarb,Bismuth Salt Ditiocarb,Diethyldithiocarbamate, Sodium,Diethyldithiocarbamate, Zinc,Lead Salt Ditiocarb,Potassium Salt Ditiocarb,Sodium Salt Ditiocarb,Sodium, Ditiocarb,Zinc Salt Ditiocarb
D004305 Dose-Response Relationship, Drug The relationship between the dose of an administered drug and the response of the organism to the drug. Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D006873 Hydroquinones Derivatives of hydroquinone (1,4-dihydrobenzene) made by reduction of BENZOQUINONES. Quinol,p-Dihydroxybenzenes,para-Dihydroxybenzenes,Quinols,p Dihydroxybenzenes,para Dihydroxybenzenes

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