Table 1.
Reactive oxygen species (ROS) agents, reducing agents and gasotransmitters that are produced by cells and/or are experimentally used chemicals for modulating BK channels.
| Oxidizing/Reducing agents at BK channels | |||
|---|---|---|---|
| Chemical nomenclature | Abbrev./ Formula | Company | Notes/literature |
| Oxidizing agents | |||
| Hydrogen peroxide | H2O2 | Fisher Scientific; Sigma | commonly used oxidizing agent. H2O2 is naturally produced by the cell metabolism, is membrane permeable and relatively stable [120,121]. |
| Superoxide anion | O2−• | Sigma | radical; range of 10−11 to 10−10 M; [122] antagonist: superoxide dismutase. |
| Glutathione disulfide | GSSG | Sigma | physiological oxidized form of GSH [123]. |
| Chloramine-T | Ch-T | Sigma | oxidizes methionine [119]; oxidation leads to polar methionine sulfoxide (Met-O), reversed by methionine sulfoxide reductases [109]. |
| N-chlorosuccinimide | NCS | Sigma | oxidizes methionine [119]. |
| 4,4'-dithiodipyridine | 4,4DTDP | Sigma | [124] |
| 2,2'-dithiodipyridine | 2,2DTDP | Sigma | [125,126] |
| 5'5-dithio-bis(2-nitrobenzoic acid | DTNB | Sigma | cysteine-specific reagent [109,123,127]. |
| (2-Aminoethyl) methan-ethiosulfonate hydrochloide | MTSEA+ | Toronto Research | cysteine-specific, covalently modifies free thiol groups [125]. |
| 2-(trimethylammonium) ethyl methanethiosulfonate, bromide | MTSET | Toronto Research | [128] |
| p-chloromercuribenzoic acid | pCMB | Sigma | cysteine-specific [109]. |
| Sodium (2-sulfanatoethyl) methanethiosulfonate | MTSES | Toronto Research | [128] |
| Thimerosal | Sigma | sulfhydryl reagent; its oxidizing ability is related to the presence of mercury [124,129]. | |
| Diamide | Sigma | [125] | |
| Hydroxyl radicals | OH− ● | [130] | |
| Peroxynitrite | ONOO− | formed at a low rate by the reaction of NO● with (O2−●) in a 1:1 stoichiometry for synthesis cf. [131]. | |
| Rose bengal | 4,5,6,7-tetrachloro-2',4',5',7'-tetraiodo fluorescein | Sigma | Stain, clinical trials in some cancer therapies; generates singlet oxygen from triplet oxygen [132]. |
| Normoxia | test solutions equilibrated with room air [126,133,134]. | ||
| Reduci ng agents | |||
| Chemical nomenclature | Abbrev./ Formula | Company | notes/literature |
| Dithiothreitol | DTT | Sigma | reduction of disulfide links [124,126,129,135]. |
| β-mercaptoethanol | β-ME | Sigma | [125] |
| Glutathione | GSH | Physiological reduced form [136]. | |
| Nicotinamide adenine dinucleotide hydrate | NADH | Sigma | reduced form of physiological oxidized form NAD+ [137]. |
| Thioredoxine | TRX | Sigma | in reduced form act as oxidoreductases [118]. |
| Methionine sulfoxide reductase | MSRA | Sigma | converts Met-O to Met [109]. |
| Hypoxia | bubbling of experimental solutions with nitrogen gas [126,133,134]. | ||
| Gasotransmitters | |||
| Nitric oxide, gas—donors | NO | Alexis | short lived radical (seconds) acts directly or via the sGC—cGMP—PKG signaling pathway [138]. NO range of (10−9 to 10−7 M) [124,132]. |
| Diethylamine NONOate | DEA-NO | Corp. | |
| Sodium nitroprusside | SNP | Cayman | |
| S-Nitroso-N-Acetyl-d,l-Penicillamine, etc. | SNAP | Sigma | |
| Hydrogen sulfide, gas—donors | H2S | Sigma | [60,129,139] |
| Sodium hydrogen sulfide | NaHS | ||
| Sodium sulfide, etc. | Na2S | ||
| Carbon monoxide, gas—donors | CO | Sigma | [140] |
| Carbon monoxide releasing molecules | CORM-A1 | [141,142] | |
| CORM-2 | [143] | ||
| CORM-3 | [144] | ||
| N-ethylmaleimide | NEM | Sigma | alkylating agent [128] |