title: Cyclosporin A does not protect the disruption of the inner mitochondrial membrane potential induced by potassium ionophores in intact K562 cells.
abstract: Mitochondrial dysfunction has been widely associated with programmed cell death. Studies of intact cells are important for the understanding of the process of cell death and its relation to mitochondrial physiology. Using cytofluorometric approaches we studied the mitochondrial behavior in an erythroleukemic cell line. The effects of protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP), potassium exchanger (nigericin), potassium ionophore (valinomycin), Na+K+-ATPase inhibitor (ouabain) and mitochondrial permeability transition pore inhibitor (cyclosporin A) were evaluated. Cyclosporin A (CSA) was very effective in attenuating the disruption of inner mitochondrial membrane potential induced by CCCP. However, CSA failed to protect the loss of inner mitochondrial membrane potential induced by potassium intracellular flux manipulation. Our findings suggest that mitochondrial cyclophilin is not involved in the cell events mediated by deregulation of potassium flux, underlining the need for further studies in intact tumor cells for a better understanding of the involvement of mitochondria physiology in cell death events.
authors.affiliation: Departamento de Biologia Molecular, Centro de Ciências Exatas e da Natureza, Universidade Federal da Paraíba, Campus I, Cidade Universitária, CEP 58059-900, João Pessoa, PB, Brazil. marques@dbm.ufpb.br
authors.forename: Luis F
authors.initials: LF
authors.lastname: Marques-Santos
authors.forename: Vivian M
authors.initials: VM
authors.lastname: Coqueiro
authors.forename: Vivian M
authors.initials: VM
authors.lastname: Rumjanek
mesh_terms: D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D016572:Cyclosporine / Q000494:pharmacology*; D018432:Drug Resistance, Multiple; D006801:Humans; D007476:Ionophores / Q000494:pharmacology*; D020014:K562 Cells; D008564:Membrane Potentials / Q000187:drug effects; D051336:Mitochondrial Membranes / Q000187:drug effects* / Q000378:metabolism; D009550:Nigericin / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology*; D013997:Time Factors; D014634:Valinomycin / Q000494:pharmacology
chemical_list: D007476:Ionophores; D014634:Valinomycin; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D010042:Ouabain; D016572:Cyclosporine; D009550:Nigericin; D011188:Potassium