Affiliation:
1. Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, and Department of Physiology, Faculty of Medicine, University of Manitoba, 351 Tache Avenue, Winnipeg, MB R2H 2A6, Canada.
Abstract
This study was undertaken to test whether Ca2+-handling abnormalities in cardiomyocytes after ischemia–reperfusion (I/R) are prevented by antioxidants such as N-acetyl l-cysteine (NAC), which is known to reduce oxidative stress by increasing the glutathione redox status, and N-(2-mercaptopropionyl)-glycine (MPG), which scavenges both peroxynitrite and hydroxyl radicals. For this purpose, isolated rat hearts were subjected to 30 min of global ischemia followed by 30 min of reperfusion, and cardiomyocytes were prepared to monitor changes in the intracellular concentration of free Ca2+([Ca2+]i). Marked depression in the left ventricular developed pressure and elevation in the left ventricular end-diastolic pressure in I/R hearts were attenuated by treatment with NAC or MPG. Cardiomyocytes obtained from I/R hearts showed an increase in the basal level of [Ca2+]ias well as augmentation of the low Na+-induced increase in [Ca2+]i, with no change in the KCl-induced increase in [Ca2+]i. These I/R-induced alterations in Ca2+handling by cardiomyocytes were attenuated by treatment of hearts with NAC or MPG. Furthermore, reduction in the isoproterenol-, ATP-, ouabain-, and caffeine-induced increases in [Ca2+]iin cardiomyocytes from I/R hearts were limited by treatment with NAC or MPG. The increases in the basal [Ca2+]i, unlike the KCl-induced increase in [Ca2+]i, were fully or partially prevented by both NAC and MPG upon exposing cardiomyocytes to hypoxia–reoxygenation, H2O2, or a mixture of xanthine and xanthine oxidase. These results suggest that improvement in cardiac function of I/R hearts treated with NAC or MPG was associated with attenuation of changes in Ca2+handling by cardiomyocytes, and the results support the view that oxidative stress due to oxyradical generation and peroxynitrite formation plays an important role in the development of intracellular Ca2+overload in cardiomyocytes as a consequence of I/R injury.
Publisher
Canadian Science Publishing
Subject
Physiology (medical),Pharmacology,General Medicine,Physiology
Cited by
23 articles.
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