© 1999 by European Society of Cardiology
Copyright © 1999, European Society of Cardiology
Inhibitors of poly (ADP-ribose) synthetase protect rat cardiomyocytes against oxidant stress
William Harvey Research Institute, St Bartholomew's and the Royal London School of Medicine and Dentistry, Charterhouse Square, London, EC1M 6BQ, UK
* Corresponding author. Tel.: +44-171-982-6119; fax: +44-171-251-1685; e-mail: cthiemermann@mds.qmw.ac.uk
Objective: Inhibitors of poly (ADP-ribose) synthetase (PARS) activity reduce the infarct size caused by regional myocardial ischaemia and reperfusion in the rabbit and rat in vivo. The mechanism of action of these inhibitors is unclear. Here we investigate the effects of the PARS inhibitor 3-aminobenzamide (3-AB) on infarct size caused by ischaemia and reperfusion of the isolated, perfused heart of the rat. We also investigate the role of PARS in the hydrogen peroxide-mediated cell injury/necrosis in rat cardiac myoblasts. Methods: Rat isolated hearts perfused at constant pressure (80 mmHg) were subjected to 35 min of regional ischaemia and 2 h of reperfusion. Infarct size was determined at the end of the experiment using nitro-blue tetrazolium. 3-AB (300 µM) or 3-aminobenzoic acid (3-ABA, 300 µM) were infused during the reperfusion period. Rat cardiac myoblasts (H9c2 cells) were preincubated with the PARS inhibitors, 3-AB, nicotinamide (Nic) or 1,5-dihydroxyisoquinoline (ISO) or the inactive analogues 3-ABA or nicotinic acid (NicA) prior to exposure with hydrogen peroxide (1 mM). Cell injury was assessed by measuring mitochondrial respiration and cell necrosis by measuring the release of LDH. PARS activity was determined by measuring the incorporation of NAD into nuclear proteins. Results: Regional ischaemia and reperfusion of the isolated rat heart resulted in an infarct size of 54% which was reduced by 3-AB, but not by 3-ABA. Exposure of rat cardiac myoblasts to hydrogen peroxide caused an increase in PARS activity and cell injury/necrosis which was attenuated by pretreatment with the PARS inhibitors. Conclusion: Inhibition of the activity of PARS attenuates the cell death associated with oxidant stress in rat cardiac myoblasts and heart.
KEYWORDS Rat; Heart; H9c2 cells; Reperfusion injury; Reactive oxygen species
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