title: Vanadate induces necrotic death in neonatal rat cardiomyocytes through mitochondrial membrane depolarization.
abstract: Besides the well-known inotropic effects of vanadium in cardiac muscle, previous studies have shown that vanadate can stimulate cell growth or induce cell death. In this work, we studied the toxicity to neonatal rat ventricular myocytes (cardiomyocytes) of two vanadate solutions containing different oligovanadates distribution, decavanadate (containing decameric vanadate, V 10) and metavanadate (containing monomeric vanadate and also di-, tetra-, and pentavanadate). Incubation for 24 h with decavanadate or metavanadate induced necrotic cell death of cardiomyocytes, without significant caspase-3 activation. Only 10 microM total vanadium of either decavanadate (1 microM V 10) or metavanadate (10 microM total vanadium) was needed to produce 50% loss of cell viability after 24 h (assessed with MTT and propidium iodide assays). Atomic absorption spectroscopy showed that vanadium accumulation in cardiomyocytes after 24 h was the same when incubation was done with decavanadate or metavanadate. A decrease of 75% of the rate of mitochondrial superoxide anion generation, monitored with dihydroethidium, and a sustained rise of cytosolic calcium (monitored with Fura-2-loaded cardiomyocytes) was observed after 24 h of incubation of cardiomyocytes with decavanadate or metavanadate concentrations close to those inducing 50% loss of cell viability produced. In addition, mitochondrial membrane depolarization within cardiomyocytes, monitored with tetramethylrhodamine ethyl esther or with 3,3',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolcarbocyanine iodide, were observed after only 6 h of incubation with decavanadate or metavanadate. The concentration needed for 50% mitochondrial depolarization was 6.5 +/- 1 microM total vanadium for both decavanadate (0.65 microM V 10) and metavanadate. In conclusion, mitochondrial membrane depolarization was an early event in decavanadate- and monovanadate-induced necrotic cell death of cardiomyocytes.
authors.affiliation: Comparative Cardiovascular Physiopathology Group (GFCC), Faculty of Environmental and Marine Sciences, Centre of Marine Sciences (CCMAR), University of Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. sssoares@ualg.pt
authors.forename: Sandra Sofia
authors.initials: SS
authors.lastname: Soares
authors.forename: Fernando
authors.initials: F
authors.lastname: Henao
authors.forename: Manuel
authors.initials: M
authors.lastname: Aureliano
authors.forename: Carlos
authors.initials: C
authors.lastname: Gutiérrez-Merino
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001562:Benzimidazoles; D002118:Calcium / Q000378:metabolism; D002232:Carbocyanines; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004735:Energy Transfer; D005456:Fluorescent Dyes; D009682:Magnetic Resonance Spectroscopy; D008564:Membrane Potentials / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D009336:Necrosis / Q000139:chemically induced / Q000473:pathology; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D014638:Vanadates / Q000378:metabolism / Q000633:toxicity*
chemical_list: D001562:Benzimidazoles; D002232:Carbocyanines; D005456:Fluorescent Dyes; D017382:Reactive Oxygen Species; C068624:5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine; D014638:Vanadates; D053148:Caspase 3; D002118:Calcium