OXIDATIVE STRESS AND ANTIOXIDANTS IN IRON OVERLOAD

说明(改编自应用程序) 心脏功能障碍提供了铁的最直接证据 毒性和心力衰竭一直是 血色素沉着症患者。我们已经证明，即使是轻微的铁超载 促进对缺血后心脏的损伤。我们还表明，β-受体阻滞剂 普萘洛尔可在内皮溶酶体中蓄积，并为细胞内 保护心脏免受氧化损伤。此应用程序基于 两种假说：1)内皮细胞中的溶酶体是主要的储存部位 并提供可释放的氧化还原活性低分子的主要来源 铁，它可以加强对氧化应激的心血管损伤 (例如，缺血/再灌注和外源性氧化剂)。2)稳定 氧化应激前部分亲脂β受体阻滞剂对溶酶体铁的影响 将减轻细胞和心脏损伤。通过使用培养的 血管内皮细胞和大鼠心脏模型，我们建议进行以下研究 目的：1)测定溶酶体铁对内皮细胞的作用 铁超载和随后的氧化应激导致的心脏损伤。2) 确定选定的β-受体阻滞剂和类似物是否使溶酶体碱化 会伴随着铁负荷中氧化应激的减少 内皮细胞。3)确定使用β-受体阻滞剂类似物治疗是否 减轻铁负荷大鼠心脏的氧化应激。4)评估是否 长期的药物预治疗可降低细胞和组织铁 积累。将使用各种复杂的技术来评估 自由基产生与氧化损伤(ESR自旋捕获、脂质 过氧化产物和抗氧化剂定量)、总分子和低分子 铁的定量(X射线微量分析，钙黄绿素荧光指示剂，无ESR 技术)、组织和细胞毒性(心肌功能和细胞 生存)。我们相信我们建议的研究可能会导致重新评估 β-受体阻滞剂在铁超载治疗中的潜在应用。

DESCRIPTION (adapted from the 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.