Ye Yumei, Lin Yu, Manickavasagam Saraswathy, Perez-Polo J Regino, Tieu Brian C, Birnbaum Yochai
Department of Biochemistry and Molecular Biology, Graduate School of Biomedical Science, University of Texas Medical Branch, Galveston, TX, USA.
Am J Physiol Heart Circ Physiol. 2008 Dec;295(6):H2436-46. doi: 10.1152/ajpheart.00690.2008. Epub 2008 Oct 17.
Endothelial nitric oxide synthase (eNOS) activation with subsequent inducible NOS (iNOS), cytosolic phospholipase A2 (cPLA2), and cyclooxygenase-2 (COX2) activation is essential to statin inhibition of myocardial infarct size (IS). In the rat, the peroxisome proliferator-activated receptor-gamma agonist pioglitazone (Pio) limits IS, upregulates and activates cPLA2 and COX2, and increases myocardial 6-keto-PGF1alpha levels without activating eNOS and iNOS. We asked whether Pio also limits IS in eNOS-/- and iNOS-/- mice. Male C57BL/6 wild-type (WT), eNOS-/-, and iNOS-/- mice received 10 mg.kg(-1).day(-1) Pio (Pio+) or water alone (Pio-) for 3 days. Mice underwent 30 min coronary artery occlusion and 4 h reperfusion, or hearts were harvested and subjected to ELISA and immunoblotting. As a result, Pio reduced IS in the WT (15.4+/-1.4% vs. 39.0+/-1.1%; P<0.001), as well as in the eNOS-/- (32.0+/-1.6% vs. 44.2+/-1.9%; P<0.001) and iNOS-/- (18.0+/-1.2% vs. 45.5+/-2.3%; P<0.001) mice. The protective effect of Pio in eNOS-/- mice was smaller than in the WT (P<0.001) and iNOS-/- (P<0.001) mice. Pio increased myocardial Ser633 and Ser1177 phosphorylated eNOS levels in the WT and iNOS-/- mice. iNOS was undetectable in all six groups. Pio increased cPLA2, COX2, and PGI2 synthase levels in the WT, as well as in the eNOS-/- and iNOS-/-, mice. Pio increased the myocardial 6-keto-PGF1alpha levels and cPLA2 and COX2 activity in the WT, eNOS-/-, and iNOS-/- mice. In conclusion, the myocardial protective effect of Pio is iNOS independent and may be only partially dependent on eNOS. Because eNOS activity decreases with age, diabetes, and advanced atherosclerosis, this effect may be relevant in a clinical setting and should be further characterized.
内皮型一氧化氮合酶（eNOS）激活以及随后诱导型一氧化氮合酶（iNOS）、胞质型磷脂酶A2（cPLA2）和环氧化酶-2（COX2）激活对于他汀类药物抑制心肌梗死面积（IS）至关重要。在大鼠中，过氧化物酶体增殖物激活受体γ激动剂吡格列酮（Pio）可限制IS，上调并激活cPLA2和COX2，并增加心肌6-酮-前列腺素F1α水平，而不激活eNOS和iNOS。我们探讨了Pio在eNOS基因敲除（eNOS-/-）和iNOS基因敲除（iNOS-/-）小鼠中是否也能限制IS。雄性C57BL/6野生型（WT）、eNOS-/-和iNOS-/-小鼠接受10mg·kg-1·天-1的Pio（Pio+）或仅饮水（Pio-），持续3天。小鼠经历30分钟冠状动脉闭塞和4小时再灌注，或者摘取心脏并进行酶联免疫吸附测定（ELISA）和免疫印迹分析。结果显示，Pio可减小WT小鼠的IS（15.4±1.4%对39.0±1.1%；P<0.001），eNOS-/-小鼠的IS（32.0±1.6%对44.2±1.9%；P<0.001）以及iNOS-/-小鼠的IS（18.0±1.2%对45.5±2.3%；P<0.001）。Pio对eNOS-/-小鼠的保护作用小于对WT小鼠（P<0.001）和iNOS-/-小鼠（P<0.001）。Pio可增加WT和iNOS-/-小鼠心肌中Ser633和Ser1177磷酸化eNOS水平。在所有六组中均未检测到iNOS。Pio可增加WT、eNOS-/-和iNOS-/-小鼠中cPLA2、COX2和前列环素I2合成酶水平。Pio可增加WT、eNOS-/-和iNOS-/-小鼠心肌6-酮-前列腺素F1α水平以及cPLA2和COX2活性。总之，Pio的心肌保护作用不依赖iNOS，可能仅部分依赖eNOS。由于eNOS活性会随年龄、糖尿病和晚期动脉粥样硬化而降低，这种作用在临床环境中可能具有相关性，应进一步加以研究。
