RESUMO
AIMS: Hypoxia-inducible factor-1 (HIF-1) has been reported to promote tolerance against acute myocardial ischaemia-reperfusion injury (IRI). However, the mechanism through which HIF-1 stabilization actually confers this cardioprotection is not clear. We investigated whether HIF-1α stabilization protects the heart against acute IRI by preventing the opening of the mitochondrial permeability transition pore (MPTP) and the potential mechanisms involved. METHODS AND RESULTS: Stabilization of myocardial HIF-1 was achieved by pharmacological inhibition of prolyl hydroxylase (PHD) domain-containing enzyme using GSK360A or using cardiac-specific ablation of von Hippel-Lindau protein (VHL(fl/fl)) in mice. Treatment of HL-1 cardiac cells with GSK360A stabilized HIF-1, increased the expression of HIF-1 target genes pyruvate dehydrogenase kinase-1 (PDK1) and hexokinase II (HKII), and reprogrammed cell metabolism to aerobic glycolysis, thereby resulting in the production of less mitochondrial oxidative stress during IRI, and less MPTP opening, effects which were shown to be dependent on HKII. These findings were further confirmed when HIF-1 stabilization in the rat and murine heart resulted in smaller myocardial infarct sizes (both in vivo and ex vivo), decreased mitochondrial oxidative stress, and inhibited MPTP opening following IRI, effects which were also found to be dependent on HKII. CONCLUSIONS: We have demonstrated that acute HIF-1α stabilization using either a pharmacological or genetic approach protected the heart against acute IRI by promoting aerobic glycolysis, decreasing mitochondrial oxidative stress, activating HKII, and inhibiting MPTP opening.
Assuntos
Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Mitocôndrias Cardíacas/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Infarto do Miocárdio/prevenção & controle , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Miocárdio/metabolismo , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Glicólise , Hexoquinase/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Masculino , Camundongos Knockout , Mitocôndrias Cardíacas/efeitos dos fármacos , Poro de Transição de Permeabilidade Mitocondrial , Infarto do Miocárdio/genética , Infarto do Miocárdio/metabolismo , Infarto do Miocárdio/patologia , Traumatismo por Reperfusão Miocárdica/genética , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/patologia , Miocárdio/patologia , Estresse Oxidativo , Inibidores de Prolil-Hidrolase/farmacologia , Proteínas Serina-Treonina Quinases/metabolismo , Estabilidade Proteica , Piruvato Desidrogenase Quinase de Transferência de Acetil , Ratos Sprague-Dawley , Transdução de Sinais , Fatores de Tempo , Proteína Supressora de Tumor Von Hippel-Lindau/genéticaRESUMO
The amphipod Gammarus pulex has been extensively used for ecotoxicological studies. However, the tests used are either labourious to perform and/or require relatively expensive equipment. We report the development of a new low cost infra red actograph system that measures relative activity, and can detect the behavioural effects of very low concentrations of heavy metals. Trials demonstrated that the home built system can distinguish significantly different behaviour between G. pulex exposed to clean water and that contaminated with as low as 10 microg L(-1) copper. This highly sensitive low cost automated system has the potential to become an important tool for ecotoxicity testing and water quality monitoring.
