Generation mechanisms of nitrogen dioxide-like species from cardiovascular system.

本研究探讨了心脏中是否存在参与过氧化物酶依赖性酪氨酸硝化的酶或蛋白质，以及这些酶所具有的生化特性。蛋白质有助于酪氨酸硝化被证明在大鼠心脏的可溶性组分，并显示出最大的酪氨酸硝化能力在pH 6.0，并被确定为血红蛋白和肌红蛋白。当大鼠心脏的冷冻切片在低浓度的NO2-和H2 O2存在下孵育时，在肌细胞中以颗粒图案观察到硝基酪氨酸的免疫组织化学定位。此外，我们还研究了在缺血心脏或缺血再灌注后心脏的梗死灶中，过氧化物酶蛋白的存在对酪氨酸硝化的贡献。在冠状动脉中观察到过氧化物酶依赖性酪氨酸硝化能力，并确定为中性粒细胞的髓过氧化物酶。然而，硝基酪氨酸的免疫染色定位观察到梗死病变，而不是在冠状动脉的固定心脏切片或冷冻切片的心脏。因此，在去除血红蛋白和肌球蛋白后，尽管推测来自细胞色素c分解的微过氧化物酶可能有助于肌细胞的酪氨酸硝化，但由于所贡献的蛋白质的分子量，不太可能考虑它。今后，应研究高分子量蛋白质。

We investigated whether some enzymes or proteins contribute to peroxidase-dependent tyrosine nitration are existed in the heart and what biochemical characteristics are contained in the peroxidases. Proteins contribute to tyrosine nitration are demonstrated in soluble fractions of rat's heart and showed a maximal tyrosine nitration capacity in pH 6.0 and were determined as hemoglobin and myoglobin. When cryosections of rat's heart were incubated in the presence of low concentrations of N02- and H202, immunohistochemical localization for nitrotyrosine was observed in a granular pattern in the myocytes. Moreover, we investigated the existence of peroxidase proteins contribute in tyrosine nitration in an ischemic heart or infracted lesions of the heart after isechemia reperfusion. Peroxidase-dependent tyrosine nitration capacity was observed in the coronary artery and determined as myeloperoxidase from neutrophils. However, immunostaining localization for nitrotyrosine was observed in infarcted lesions and not in the coronary artery of fixed heart sections or cryosections of the heart. Therefore, after removal of hemoglobin and myoblobin, although it is speculated that microperoxidases from the decomposition of cytochrome c may contribute to the tyrosine nitration of myocytes, it is not likely to consider it because of molecular weight of contributed proteins. In future, high molecular weight proteins should be investigated.