Superoxide-dependent and superoxide-independent pathways for reduction of nitroblue tetrazolium in isolated rat cardiac myocytes
| Autor: | William S. Thayer |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Male
Azides Dicumarol Cell Survival Biophysics Tetrazolium Salts chemical and pharmacologic phenomena Digitonin Biochemistry Superoxide dismutase chemistry.chemical_compound Superoxides medicine Animals Viability assay Potassium Cyanide Sodium Azide Molecular Biology Cells Cultured biology Chemistry Superoxide Myocardium Nitroblue Tetrazolium Heart Rats Inbred Strains Dicoumarol NAD Rats Cytosol Kinetics Doxorubicin biology.protein Formazan Oxidation-Reduction Intracellular NADP medicine.drug |
| Zdroj: | Archives of biochemistry and biophysics. 276(1) |
| ISSN: | 0003-9861 |
| Popis: | Spectroscopic studies indicated that nitroblue tetrazolium (NBT) could be reduced to blue formazan by several distinct reactions in suspensions of isolated rat cardiac myocytes. Both NADPH- and NADH-linked pathways for reduction of NBT were observed. NADPH-linked NBT reduction showed little activity in the absence of digitonin, but could be stimulated an average of 9.5-fold by digitonin permeabilization of the plasma membrane. NADH-linked NBT reduction occurred in the absence of digitonin, and could be increased an average of 3.5-fold by digitonin treatment. Analysis of the effects of cell viability on the extent of digitonin stimulation with these substrates suggested that the NADPH-linked reaction involved a cytosolic component, while the NADH-linked reaction involved an intracellular membrane enzyme system. With either NADPH or NADH, NBT reduction was completely inhibited by dicoumarol (100 μ m ). Dicoumarol-insensitive NBT reduction could subsequently be observed following the addition of 2 m m cyanide, a level of cyanide known to inhibit cytosolic superoxide dismutase. Cyanide-stimulated, dicoumarol-insensitive NBT reduction was augmented by the presence of either antimycin or doxorubicin, two agents which enhance superoxide formation by different mechanisms. The results indicate the existence of multiple pathways for both superoxide-independent and superoxide-dependent reduction of NBT. Dicoumarol-insensitive, cyanide-stimulated NBT reduction may be useful as a spectroscopic probe for intracellular superoxide formation. |
| Databáze: | OpenAIRE |
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