Original ArticleUncoupling the Coupled Calcium and Zinc Dyshomeostasis in Cardiac Myocytes and Mitochondria Seen in AldosteronismKamalov, German MD, PhD*; Ahokas, Robert A PhD†; Zhao, Wenyuan MD, PhD*; Zhao, Tieqiang MD, PhD*; Shahbaz, Atta U MD*; Johnson, Patti L BS*; Bhattacharya, Syamal K PhD*‡; Sun, Yao MD, PhD*; Gerling, Ivan C PhD§; Weber, Karl T MD*Author Information From the *Division of Cardiovascular Diseases; †Departments of Obstetrics and Gynecology; ‡Surgery; and §Division of Endocrinology; University of Tennessee Health Science Center, Memphis, TN. Received for publication September 22, 2009; accepted November 5, 2009. Supported, in part, by National Institutes of Health grants R01-HL73043 and R01-HL90867 (K.T.W.). Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Institutes of Health. The authors report no conflicts of interest. Reprints: Karl T. Weber, MD, Division of Cardiovascular Diseases, University of Tennessee Health Science Center, Coleman College of Medicine Building, 956 Court Avenue, Suite A312, Memphis, TN 38163 (e-mail: [email protected]). Journal of Cardiovascular Pharmacology: March 2010 - Volume 55 - Issue 3 - p 248-254 doi: 10.1097/FJC.0b013e3181cf0090 Buy Metrics Abstract Intracellular [Ca2+]i overloading in cardiomyocytes is a fundamental pathogenic event associated with chronic aldosterone/salt treatment (ALDOST) and accounts for an induction of oxidative stress that leads to necrotic cell death and consequent myocardial scarring. This prooxidant response to Ca2+ overloading in cardiac myocytes and mitochondria is intrinsically coupled to simultaneous increased Zn2+ entry serving as an antioxidant. Herein, we investigated whether Ca2+ and Zn2+ dyshomeostasis and prooxidant to antioxidant dysequilibrium seen at 4 weeks, the pathologic stage of ALDOST, could be uncoupled in favor of antioxidants, using cotreatment with a ZnSO4 supplement; pyrrolidine dithiocarbamate (PDTC), a Zn2+ ionophore; or ZnSO4 in combination with amlodipine (Amlod), a Ca2+ channel blocker. We monitored and compared responses in cardiomyocyte free [Ca2+]i and [Zn2+]i together with biomarkers of oxidative stress in cardiac myocytes and mitochondria. At week 4 of ALDOST and compared with controls, we found (1) an elevation in [Ca2+]i coupled with [Zn2+]i and (2) increased mitochondrial H2O2 production and increased mitochondrial and cardiac 8-isoprostane levels. Cotreatment with the ZnSO4 supplement alone, PDTC, or ZnSO4+Amlod augmented the rise in cardiomyocyte [Zn2+]i beyond that seen with ALDOST alone, whereas attenuating the rise in [Ca2+]i, which together served to reduce oxidative stress. Thus, a coupled dyshomeostasis of intracellular Ca2+ and Zn2+ was demonstrated in cardiac myocytes and mitochondria during 4-week ALDOST, where prooxidants overwhelm antioxidant defenses. This intrinsically coupled Ca2+ and Zn2+ dyshomeostasis could be uncoupled in favor of antioxidant defenses by selectively increasing free [Zn2+]i and/or reducing [Ca2+]i using cotreatment with ZnSO4 or PDTC alone or ZnSO4+Amlod in combination. © 2010 Lippincott Williams & Wilkins, Inc.