Center for Cardiovascular and Pulmonary Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America.
PLoS One. 2011;6(8):e23116. doi: 10.1371/journal.pone.0023116. Epub 2011 Aug 5.
Diabetes mellitus and fine particulate matter from diesel exhaust (DEP) are both important contributors to the development of cardiovascular disease (CVD). Diabetes mellitus is a progressive disease with a high mortality rate in patients suffering from CVD, resulting in diabetic cardiomyopathy. Elevated DEP levels in the air are attributed to the development of various CVDs, presumably since fine DEP (<2.5 µm in diameter) can be inhaled and gain access to the circulatory system. However, mechanisms defining how DEP affects diabetic or control cardiomyocyte function remain poorly understood. The purpose of the present study was to evaluate cardiomyocyte function and reactive oxygen species (ROS) generation in isolated rat ventricular myocytes exposed overnight to fine DEP (0.1 µg/ml), and/or high glucose (HG, 25.5 mM). Our hypothesis was that DEP exposure exacerbates contractile dysfunction via ROS generation in cardiomyocytes exposed to HG. Ventricular myocytes were isolated from male adult Sprague-Dawley rats cultured overnight and sarcomeric contractile properties were evaluated, including: peak shortening normalized to baseline (PS), time-to-90% shortening (TPS(90)), time-to-90% relengthening (TR(90)) and maximal velocities of shortening/relengthening (±dL/dt), using an IonOptix field-stimulator system. ROS generation was determined using hydroethidine/ethidium confocal microscopy. We found that DEP exposure significantly increased TR(90), decreased PS and ±dL/dt, and enhanced intracellular ROS generation in myocytes exposed to HG. Further studies indicated that co-culture with antioxidants (0.25 mM Tiron and 0.5 mM N-Acetyl-L-cysteine) completely restored contractile function in DEP, HG and HG+DEP-treated myocytes. ROS generation was blocked in HG-treated cells with mitochondrial inhibition, while ROS generation was blocked in DEP-treated cells with NADPH oxidase inhibition. Our results suggest that DEP exacerbates myocardial dysfunction in isolated cardiomyocytes exposed to HG-containing media, which is potentially mediated by various ROS generation pathways.
糖尿病和柴油机尾气中的细颗粒物（DEP）都是心血管疾病（CVD）发展的重要因素。糖尿病是一种进行性疾病，患有 CVD 的患者死亡率很高，导致糖尿病性心肌病。空气中升高的 DEP 水平归因于各种 CVD 的发展，大概是因为细的 DEP（直径<2.5 µm）可以被吸入并进入循环系统。然而，定义 DEP 如何影响糖尿病或对照心肌细胞功能的机制仍知之甚少。本研究的目的是评估暴露于细 DEP（0.1 µg/ml）和/或高葡萄糖（HG，25.5 mM）的分离大鼠心室肌细胞中心肌细胞的功能和活性氧（ROS）生成。我们的假设是，DEP 暴露通过暴露于 HG 的心肌细胞中 ROS 的产生加剧收缩功能障碍。将雄性成年 Sprague-Dawley 大鼠的心室肌细胞分离出来，培养过夜，并使用 IonOptix 场刺激器系统评估肌节收缩特性，包括：峰缩短归一化为基线（PS）、达到 90%缩短的时间（TPS(90)）、达到 90%再伸长的时间（TR(90)）和缩短/再伸长的最大速度（±dL/dt）。使用 Hydroethidine/ethidium 共聚焦显微镜确定 ROS 生成。我们发现，DEP 暴露显著增加了 TR(90)，降低了 PS 和±dL/dt，并增强了暴露于 HG 的肌细胞中的细胞内 ROS 生成。进一步的研究表明，抗氧化剂（0.25 mM Tiron 和 0.5 mM N-Acetyl-L-cysteine）的共培养完全恢复了 DEP、HG 和 HG+DEP 处理的肌细胞的收缩功能。线粒体抑制阻断了 HG 处理细胞中的 ROS 生成，而 NADPH 氧化酶抑制阻断了 DEP 处理细胞中的 ROS 生成。我们的结果表明，DEP 加剧了含有 HG 的培养基中分离的心肌细胞的心肌功能障碍，这可能是通过各种 ROS 生成途径介导的。
