One- and two-electron reduction of menadione in guinea-pig and rat cardiac tissue.
1. In both guinea-pig and rat heart, mitochondrial NADH-ubiquinone-reductase and soluble DT-diaphorase accounted for 49-50% and 48-50% of menadione metabolism, respectively. Microsomal NADPH-cytochrome P450-reductase was responsible for less than 1% of menadione reduction. 2. Menadione was a high-affinity substrate for all reductases (Km values from 1 to 10 microM). 3. Marked amounts of O2-. (superoxide anion) were generated as a consequence of cardiac metabolism of menadione. 4. Menadione-induced O2-. generation was about 3-fold higher in guinea-pig than in rat heart. 5. All results were compared with data obtained on guinea-pig and rat liver.
Floreani
M
M
Department of Pharmacology, University of Padova, Italy.
Carpenedo
F
F
D000818:Animals; D042967:Electron Transport Complex I; D004583:Electrons; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008099:Liver / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D008862:Microsomes, Liver / Q000378:metabolism; D008929:Mitochondria, Heart / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010084:Oxidation-Reduction; D010101:Oxygen Consumption; D051381:Rats; D013347:Subcellular Fractions / Q000378:metabolism; D014812:Vitamin K / Q000378:metabolism*
D014812:Vitamin K; D009249:NADP; D009247:NADH, NADPH Oxidoreductases; D042967:Electron Transport Complex I