title: Release of NO from a nitrosyl ruthenium complex through oxidation of mitochondrial NADH and effects on mitochondria.
abstract: Nitrosyl ruthenium complexes are promising NO donor agents with numerous advantages for the biologic applications of NO. We have characterized the NO release from the nitrosyl ruthenium complex [Ru(NO(2))(bpy)(2)(4-pic)](+) (I) and the reactive oxygen/nitrogen species (ROS/RNS)-mediated NO actions on isolated rat liver mitochondria. The results indicated that oxidation of mitochondrial NADH promotes NO release from (I) in a manner mediated by NO(2) formation (at neutral pH) as in mammalian cells, followed by an oxygen atom transfer mechanism (OAT). The NO released from (I) uncoupled mitochondria at low concentrations/incubation times and inhibited the respiratory chain at high concentrations/incubation times. In the presence of ROS generated by mitochondria NO gave rise to peroxynitrite, which, in turn, inhibited the respiratory chain and oxidized membrane protein-thiols to elicit a Ca(2+)-independent mitochondrial permeability transition; this process was only partially inhibited by cyclosporine-A, almost fully inhibited by the thiol reagent N-ethylmaleimide (NEM) and fully inhibited by the NO scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO). These actions correlated with the release of cytochrome c from isolated mitochondria as detected by Western blotting analysis. These events, typically involved in cell necrosis and/or apoptosis denote a potential specific action of (I) and analogs against tumor cells via mitochondria-mediated processes.
authors.affiliation: Departamento de Física e Química, Universidade de São Paulo, RibeirãoPreto, SP, Brazil.
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Rodrigues
authors.forename: Cezar R
authors.initials: CR
authors.lastname: Pestana
authors.forename: Ana C M
authors.initials: AC
authors.lastname: Polizello
authors.forename: Gilberto L
authors.initials: GL
authors.lastname: Pardo-Andreu
authors.forename: Sérgio A
authors.initials: SA
authors.lastname: Uyemura
authors.forename: Antonio C
authors.initials: AC
authors.lastname: Santos
authors.forename: Luciane C
authors.initials: LC
authors.lastname: Alberici
authors.forename: Roberto S
authors.initials: RS
authors.lastname: da Silva
authors.forename: Carlos
authors.initials: C
authors.lastname: Curti
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D056831:Coordination Complexes / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D045304:Cytochromes c / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008297:Male; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism*; D009249:NADP / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism / Q000493:pharmacokinetics*; D020030:Nitric Oxide Donors / Q000378:metabolism / Q000493:pharmacokinetics*; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D026361:Reactive Nitrogen Species / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D012428:Ruthenium / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D013438:Sulfhydryl Compounds
chemical_list: D056831:Coordination Complexes; D008565:Membrane Proteins; D020030:Nitric Oxide Donors; D026361:Reactive Nitrogen Species; D017382:Reactive Oxygen Species; D013438:Sulfhydryl Compounds; D009569:Nitric Oxide; D009249:NADP; D012428:Ruthenium; D045304:Cytochromes c