Tetramethylphenylenediamine protects the isolated heart against ischaemia-induced apoptosis and reperfusion-induced necrosis.

Jurgita Barauskaite, Regina Grybauskiene, Ramune Morkuniene, Vilmante Borutaite, Guy C Brown

Institute for Biomedical Research, Lithuanian University of Health Sciences, Kaunas, Lithuania.

British journal of pharmacology 2011 Mar

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Cytochrome c when released from mitochondria into cytosol triggers assembly of the apoptosome resulting in caspase activation. Recent evidence suggests that reduced cytochrome c is unable to activate the caspase cascade. In this study, we investigated whether a chemical reductant of cytochrome c, N,N,N',N'-tetramethylphenylene-1,4-diamine (TMPD), which we have previously shown to block cytochrome c-induced caspase activation, could prevent ischaemia-induced apoptosis in the rat perfused heart. The Langendorff-perfused rat hearts were pretreated with TMPD and subjected to stop-flow ischaemia or ischaemia/reperfusion. The activation of caspases (measured as DEVD-p-nitroanilide-cleaving activity), nuclear apoptosis of cardiomyocytes (measured by dUTP nick end labelling assay), mitochondrial and cytosolic levels of cytochrome c (measured spectrophotometrically and by elisa), and reperfusion-induced necrosis (measured as the activity of creatine kinase released into perfusate) were assessed. We found that perfusion of the hearts with TMPD strongly inhibited ischaemia- or ischaemia/reperfusion-induced activation of caspases and partially prevented nuclear apoptosis in cardiomyocytes. TMPD did not prevent ischaemia- or ischaemia/reperfusion-induced release of cytochrome c from mitochondria into cytosol. TMPD also inhibited ischaemia/reperfusion-induced necrosis. These results suggest that TMPD or related molecules might be used to protect the heart against damage induced by ischaemia/reperfusion. The mechanism of this protective effect of TMPD probably involves electron reduction of cytochrome c (without decreasing its release) which then inhibits the activation of caspases. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Citation

Jurgita Barauskaite, Regina Grybauskiene, Ramune Morkuniene, Vilmante Borutaite, Guy C Brown. Tetramethylphenylenediamine protects the isolated heart against ischaemia-induced apoptosis and reperfusion-induced necrosis. British journal of pharmacology. 2011 Mar;162(5):1136-42