Cardiac contractile dysfunction in Lep/Lep obesity is accompanied by NADPH oxidase activation, oxidative modification of sarco(endo)plasmic reticulum Ca2+-ATPase and myosin heavy chain isozyme switch
Cardiac contractile dysfunction in Lep/Lep obesity is accompanied by NADPH oxidase activation, oxidative modification of sarco(endo)plasmic reticulum Ca2+-ATPase and myosin heavy chain isozyme switch
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DOI：
10.1007/s00125-006-0229-0
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发表时间：
2006-06-01
期刊：
影响因子：
8.2
通讯作者：
Ren, J
中科院分区：
文献类型：
--
作者：
Li, SY;Yang, X;Ren, J
目的/假设：肥胖是心脏病的独立危险因素，但其潜在机制尚不清楚。本研究检查了肥胖小鼠的心脏收缩、氧化应激、肌（内）质网 Ca2+-ATP 酶 (SERCA) 的氧化修饰和肌球蛋白重链 (MHC) 亚型开关。方法：评估 C57BL/6J 瘦小鼠和 Lep/Lep 肥胖小鼠（以前称为 ob/ob 小鼠）心室肌细胞的机械特性，包括峰值缩短 (PS)、达到 50 或 90% PS 的时间、达到 50 或 90% 再延长的时间 (TR50、TR90)、最大缩短/再延长速度 (+/- dL/dt)、细胞内 Ca2+ 及其衰减 (tau)。氧化应激、脂质过氧化、蛋白质损伤和SERCA活性分别通过谷胱甘肽/谷胱甘肽二硫化物、丙二醛、蛋白质羰基和Ca-45(2+)摄取来评估。 NADPH氧化酶通过免疫印迹法测定。结果：与瘦对照相比，Lep/Lep 小鼠的肌细胞表现出 PS 和 +/- dL/dt 降低、TR50、TR90 延长、静息 [Ca2+](i) 升高、t 延长、高刺激频率下的收缩能力降低以及对细胞外 Ca2+ 的反应性降低。 Lep/Lep 组心脏谷胱甘肽/谷胱甘肽二硫化物减少，而丙二醛、蛋白质羰基、膜 p47(phox) 和膜 gp91(phox) 增加。 SERCA 同工酶 2a 在 Lep/Lep 心脏中被氧化显着修饰，并与 45Ca2+ 摄取减少相关。 Lep/Lep 心脏中 MHC 同工酶显示从 α 亚型转变为 β 亚型。血管紧张素 II 与肌细胞的短期孵育模拟了在 Lep/Lep 肌细胞中观察到的机械缺陷、SERCA 氧化和 Ca-45(2+) 摄取。 NADPH 氧化酶抑制剂夹竹桃麻素与 Lep/Lep 肌细胞一起孵育可减轻收缩缺陷，但不会逆转 SERCA 氧化或活性。结论/解释：这些数据表明，肥胖相关的心脏缺陷可能与 NADPH 氧化酶激活、SERCA 氧化损伤和 MHC 同工酶开关有关。
Aims/hypothesis: Obesity is an independent risk factor for heart diseases but the underlying mechanism is not clear. This study examined cardiac contraction, oxidative stress, oxidative modification of sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) and the myosin heavy chain (MHC) isoform switch in obese mice. Methods: Mechanical properties were evaluated in ventricular myocytes from C57BL/6J lean and Lep/Lep obese mice (formerly known as ob/ob mice), including peak shortening (PS), time to 50 or 90% PS, time to 50 or 90% relengthening (TR50, TR90), maximal velocity of shortening/relengthening (+/- dL/dt), intracellular Ca2+ and its decay (tau). Oxidative stress, lipid peroxidation, protein damage and SERCA activity were assessed by glutathione/glutathione disulfide, malondialdehyde, protein carbonyl and Ca-45(2+) uptake, respectively. NADPH oxidase was determined by immunoblotting. Results: Myocytes from Lep/Lep mice displayed depressed PS and +/- dL/dt, prolonged TR50, TR90, elevated resting [Ca2+](i), prolonged t, reduced contractile capacity at high stimulus frequencies and diminished responsiveness to extracellular Ca2+ compared with lean controls. Cardiac glutathione/glutathione disulfide was decreased whereas malondialdehyde, protein carbonyl, membrane p47(phox) and membrane gp91(phox) were increased in the Lep/Lep group. SERCA isoenzyme 2a was markedly modified by oxidation in Lep/Lep hearts and associated with decreased 45Ca2+ uptake. The MHC isozyme displayed a shift from the alpha to the beta isoform in Lep/Lep hearts. Short-term incubation of angiotensin II with myocytes mimicked the mechanical defects, SERCA oxidation and Ca-45(2+) uptake seen in Lep/Lep myocytes. Incubation of the NADPH oxidase inhibitor apocynin with Lep/Lep myocytes alleviated contractile defects without reversing SERCA oxidation or activity. Conclusions/interpretation: These data indicate that obesity-related cardiac defects may be related to NADPH oxidase activation, oxidative damage to SERCA and the MHC isozyme switch.