Leptin regulates cardiomyocyte contractile function through endothelin-1 receptor-NADPH oxidase pathway
Leptin regulates cardiomyocyte contractile function through endothelin-1 receptor-NADPH oxidase pathway
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DOI：
10.1161/01.hyp.0000198555.51645.f1
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发表时间：
2006-02-01
期刊：
影响因子：
8.3
通讯作者：
Ren, J
中科院分区：
文献类型：
--
作者：
Dong, F;Zhang, XC;Ren, J
瘦素是肥胖基因的产物，在心脏功能的调节中起重要作用。然而，瘦素诱导的心肌细胞收缩反应的机制知之甚少。本研究旨在探讨内皮素-1受体和NADPH氧化酶在瘦素诱导的心肌收缩反应中的作用。分离的小鼠心肌细胞暴露于瘦素（5，50和100 nmol/L）60分钟，在不存在或存在的ETA受体拮抗剂BQ 123（1 μ mol/L），ETB受体拮抗剂BQ 788（1 μ mol/L），或NADPH氧化酶抑制剂夹竹桃苷（100 μ mol/L），然后研究机械功能。超氧化物水平通过二氢乙锭荧光染料和细胞色素c的超氧化物歧化酶可降解还原来测量。用蛋白质印迹法评价NADPH氧化酶亚基表达（p22（phox）、p47（phox）、p67（phox）和gp 91（phox））。Leptin降低峰值缩短和最大缩短/再延长速度（+/- dL/dt），延长再延长时间（TR 90），但不影响峰值缩短时间。与机械特性一致，用瘦素处理的肌细胞显示与延长的细胞内Ca 2+衰减速率相关的细胞内Ca 2+的电刺激升高降低（fura-2荧光强度的变化）。所有的异常都被夹竹桃麻素、BQ 123或BQ 788显著减弱。瘦素处理后，细胞内超氧化物生成增强，这是部分阻断夹竹桃麻素，BQ 123，或BQ 788。瘦素对p22（phox）和gp 91（phox）没有影响，但上调p67（phox）和p47（phox）的蛋白表达，这两者都被夹竹桃麻素、BQ 123或BQ 788抑制。这些结果表明，瘦素通过内皮素-1受体和NADPH氧化酶介导的途径抑制心室肌细胞的心脏收缩功能。
Leptin, the obese gene product, plays an important role in the regulation of cardiac function. However, the mechanism behind leptin-induced cardiomyocyte contractile response is poorly understood. This study was designed to examine whether endothelin-1 receptor and NADPH oxidase play any role in leptin-induced cardiac contractile response. Isolated murine cardiomyocytes were exposed to leptin ( 5, 50, and 100 nmol/L) for 60 minutes in the absence or presence of the ETA receptor antagonist BQ123 ( 1 mu mol/L), the ETB receptor antagonist BQ788 ( 1 mu mol/L), or the NADPH oxidase inhibitor apocynin ( 100 mu mol/L) before mechanical function was studied. Superoxide levels were measured by dihydroethidium fluorescent dye and the superoxide dismutase - inhibitable reduction of cytochrome c. NADPH oxidase subunit expression (p22(phox), p47(phox), p67(phox), and gp91(phox)) was evaluated with Western blot. Leptin depressed peak shortening and maximal velocity of shortening/relengthening ( +/- dL/dt), prolonged the duration of relengthening (TR90) without affecting the time-to-peak cell shortening. Consistent with the mechanical characteristics, myocytes treated with leptin displayed a reduced electrically stimulated rise in intracellular Ca2+ ( change in fura-2 fluorescence intensity) associated with a prolonged intracellular Ca2+ decay rate. All of the abnormalities were significantly attenuated by apocynin, BQ123, or BQ788. Intracellular superoxide generation was enhanced after leptin treatment, which was partially blocked by apocynin, BQ123, or BQ788. Leptin had no effect on p22(phox) and gp91(phox) but upregulated protein expression of p67(phox) and p47(phox), both of which were inhibited by apocynin, BQ123, or BQ788. These results suggest that leptin suppresses cardiac contractile function in ventricular myocytes through the endothelin-1 receptor and NADPH oxidase-mediated pathway.