Leptin regulates cardiomyocyte contractile function through endothelin-1 receptor-NADPH oxidase pathway

被引:106
作者
Dong, F
Zhang, XC
Ren, J [1 ]
机构
[1] Univ Wyoming, Ctr Cardiovasc Res & Alternat Med, Laramie, WY 82071 USA
[2] Univ Wyoming, Div Pharmaceut Sci, Laramie, WY 82071 USA
关键词
endothelin; cardiac function; obesity; oxidative stress;
D O I
10.1161/01.HYP.0000198555.51645.f1
中图分类号
R6 [外科学];
学科分类号
1002 ; 100210 ;
摘要
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.
引用
收藏
页码:222 / 229
页数:8
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