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Oxidative Medicine and Cellular Longevity
Volume 2014 (2014), Article ID 290381, 15 pages
http://dx.doi.org/10.1155/2014/290381
Research Article

Enhancement of Cellular Antioxidant-Defence Preserves Diastolic Dysfunction via Regulation of Both Diastolic Zn2+ and Ca2+ and Prevention of RyR2-Leak in Hyperglycemic Cardiomyocytes

Department of Biophysics, Faculty of Medicine, Ankara University, Ankara 06100, Turkey

Received 24 September 2013; Accepted 17 December 2013; Published 13 February 2014

Academic Editor: Susana Llesuy

Copyright © 2014 Erkan Tuncay et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We examined whether cellular antioxidant-defence enhancement preserves diastolic dysfunction via regulation of both diastolic intracellular free Zn2+ and Ca2+ levels ( and ) levels N-acetyl cysteine (NAC) treatment (4 weeks) of diabetic rats preserved altered cellular redox state and also prevented diabetes-induced tissue damage and diastolic dysfunction with marked normalizations in the resting and . The kinetic parameters of transient changes in Zn2+ and Ca2+ under electrical stimulation and the spatiotemporal properties of Zn2+ and Ca2+ sparks in resting cells are found to be normal in the treated diabetic group. Biochemical analysis demonstrated that the NAC treatment also antagonized hyperphosphorylation of cardiac ryanodine receptors (RyR2) and significantly restored depleted protein levels of both RyR2 and calstabin2. Incubation of cardiomyocytes with 10 µM ZnCl2 exerted hyperphosphorylation in RyR2 as well as higher phosphorphorylations in both PKA and CaMKII in a concentration-dependent manner, similar to hyperglycemia. Our present data also showed that a subcellular oxidative stress marker, NF-κB, can be activated if the cells are exposed directly to Zn2+. We thus for the first time report that an enhancement of antioxidant defence in diabetics via directly targeting heart seems to prevent diastolic dysfunction due to modulation of RyR2 macromolecular-complex thereby leading to normalized and in cardiomyocytes.