Abstract | BACKGROUND AND PURPOSE:
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. EXPERIMENTAL APPROACH: 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. KEY RESULTS: 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. CONCLUSIONS AND IMPLICATIONS: 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.
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Authors | Jurgita Barauskaite, Regina Grybauskiene, Ramune Morkuniene, Vilmante Borutaite, Guy C Brown |
Journal | British journal of pharmacology
(Br J Pharmacol)
Vol. 162
Issue 5
Pg. 1136-42
(Mar 2011)
ISSN: 1476-5381 [Electronic] England |
PMID | 21077848
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Copyright | © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society. |
Chemical References |
- Cardiotonic Agents
- Cytochromes c
- Caspases
- Tetramethylphenylenediamine
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Topics |
- Animals
- Apoptosis
(drug effects)
- Cardiotonic Agents
(pharmacology)
- Caspases
(metabolism)
- Cytochromes c
(metabolism)
- Cytosol
(metabolism)
- Enzyme Activation
(drug effects)
- In Vitro Techniques
- Male
- Mitochondria, Heart
(drug effects, metabolism)
- Myocardial Reperfusion Injury
(metabolism, pathology, prevention & control)
- Necrosis
(prevention & control)
- Rats
- Rats, Wistar
- Tetramethylphenylenediamine
(pharmacology)
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