application) Disorders of cardiac function have provided the most direct evidence of iron toxicity, and cardiac failure has been the most common cause of death in patients with hemochromatosis. We have shown that even mild iron-overload promotes injury to the postischemic heart. We also showed that the beta-blocker propranolol could accumulate in endothelial lysosomes and provide both cellular and cardiac protection against oxidative injury. This application is based upon two hypotheses: 1) Lysosomes in the endothelial cells are major storage sites of iron and provides a primary source of releasable redox active low molecular iron, which can enhance cardiovascular injury in response to oxidative stress (e.g. ischemia/reperfusion and exogenous oxidants). 2) Stabilization of lysosomal iron by selected lipophilic beta-blockers prior to oxidant stress will attenuate cellular and cardiac injury. By using both the cultured endothelial cell and rat heart models, we propose to investigate the following aims: 1) Determine the contribution of lysosomal iron to endothelial cell and cardiac injury due to iron-overload and subsequent oxidative stress. 2) Determine if alkalinization of lysosomes by selected beta-blockers and analogs will be accompanied by decreased oxidative stress in the iron-loaded endothelial cells. 3) Determine if treatment with beta-blocker analogs will attenuate oxidative stress in hearts from iron-loaded rats. 4) Assess if long-term pre-treatment with the drugs reduce cellular and tissue iron accumulation. A variety of sophisticated techniques will be employed to assess free radical production and oxidative injury (ESR spin trapping, lipid peroxidation products and antioxidant quantification), total and low molecular iron quantification (X-ray microanalysis, Calcein fluorescent-indicator, NO-ESR technique), and tissue and cellular toxicity (myocardial function and cell survival). We believe our proposed studies may lead to a reassessment of the potential use of beta-blockers for iron-overload therapy.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL066226-04
Application #
6638722
Study Section
Special Emphasis Panel (ZDK1-GRB-1 (J2))
Program Officer
Qasba, Pankaj
Project Start
2000-07-01
Project End
2005-06-30
Budget Start
2003-07-01
Budget End
2004-06-30
Support Year
4
Fiscal Year
2003
Total Cost
$304,000
Indirect Cost
Name
George Washington University
Department
Type
Schools of Medicine
DUNS #
043990498
City
Washington
State
DC
Country
United States
Zip Code
20052
Mak, I Tong; Landgraf, Kenneth M; Chmielinska, Joanna J et al. (2012) Angiotensin II promotes iron accumulation and depresses PGIýýý and NO synthesis in endothelial cells: effects of losartan and propranolol analogs. Can J Physiol Pharmacol 90:1413-8
Kramer, Jay H; Spurney, Christopher F; Iantorno, Micaela et al. (2012) d-Propranolol protects against oxidative stress and progressive cardiac dysfunction in iron overloaded rats. Can J Physiol Pharmacol 90:1257-68
Mak, I Tong; Chmielinska, Joanna J; Nedelec, Lucie et al. (2006) D-propranolol attenuates lysosomal iron accumulation and oxidative injury in endothelial cells. J Pharmacol Exp Ther 317:522-8
Kramer, Jay H; Murthi, Sarah B; Wise, Robert M et al. (2006) Antioxidant and lysosomotropic properties of acute D-propranolol underlies its cardioprotection of postischemic hearts from moderate iron-overloaded rats. Exp Biol Med (Maywood) 231:473-84
Komarov, Andrei M; Hall, Jonathon M; Chmielinska, Joanna J et al. (2006) Iron uptake and release by macrophages is sensitive to propranolol. Mol Cell Biochem 288:213-7
Komarov, Andrei M; Hall, Jonathon M; Weglicki, William B (2004) Azidothymidine promotes free radical generation by activated macrophages and hydrogen peroxide-iron-mediated oxidation in a cell-free system. Biochim Biophys Acta 1688:257-64
Mak, I Tong; Weglicki, William B (2004) Potent antioxidant properties of 4-hydroxyl-propranolol. J Pharmacol Exp Ther 308:85-90
Mak, I Tong; Zhang, Jingyun; Weglicki, William B (2002) Protective effects of dihydropyridine Ca-blockers against endothelial cell oxidative injury due to combined nitric oxide and superoxide. Pharmacol Res 45:27-33
Dickens, Benjamin F; Weglicki, William B; Boehme, Patricia A et al. (2002) Antioxidant and lysosomotropic properties of acridine-propranolol: protection against oxidative endothelial cell injury. J Mol Cell Cardiol 34:129-37
Kramer, J H; Lightfoot, F G; Weglicki, W B (2000) Cardiac tissue iron: effects on post-ischemic function and free radical production, and its possible role during preconditioning. Cell Mol Biol (Noisy-le-grand) 46:1313-27