Formation of nitric oxide, superoxide, and peroxynitrite in myocardial ischemia-reperfusion injury in rats

Abstract

In the present study, the contribution of nitric oxide (NO), superoxide, and peroxynitrite to the inflammatory response induced by myocardial ischemia-reperfusion (MI/R) was investigated. Male Sprague-Dawley rats were anesthetized, and the left main coronary artery was ligated for 20 min and reperfused for 5 h. MI/R induced severe arrhythmias, indicated by a significantly elevated arrhythmia score in the MI/R group compared with that in the sham control group. Creatine kinase activity in the left ventricular free wall of the MI/R group was significantly reduced by 38%. In contrast, myeloperoxidase activity in the left ventricular free wall of the MI/R group was increased by 140%. Similarly, superoxide and tissue NO levels in the ischemic region of the heurt were increased by 140 and 90%, respectively. Superoxide and NO values in the nonischemic regions were similar to the sham control group. Total NO synthase (NOS) activity was elevated by 212%; moreover, inducible NOS (iNOS) activity increased 6.7-fold in the ischemic vs. nonischemic regions. MI/R also induced both systemic and remote organ (lung) inflammatory responses. Circulating neutrophils and plasma NO levels were increased by 163 and 138%, respectively, in MI/R rats compared with sham control animals. NO levels and superoxide generation were increased by 90 and 176%, respectively, in the lung tissues. The expression of iNOS and peroxynitrite generation were demonstrated by immunohistochemical staining with polyclonal anti-iNOS and monoclonal anti-nitrotyrosine antibodies, respectively. Sections of both the ischemic area of the ventricular wall and the lung tissue of MI/R animals exhibited a marked immunoreactivity with anti-iNOS and anti-nitrotyrosine antibodies, indicating the presence of iNOS and nitrotyrosine. Our data indicate that NO, superoxide, and peroxynitrite formation are elevated after reperfusion of the ischemic heart, suggesting that these inflammatory mediators may be involved in MI/R injury.

Superoxide as a Messenger of Endothelial Function

“…and subsequent inactivation has been reported (Zou and Bachschmid, 1999d), and which has been associated with endothelial dysfunction in atherosclerosis and ischemiareperfusion damage (Liu et al, 1997). The analysis presented here sets the basis for future studies in the field of vascular aging, in particular for those aimed at preventing age-related vascular dysfunction.…”

Nitric oxide in gingival crevicular fluid and nitric oxide synthase expression in the gingiva of patients with sickle cell disease

“…During NO synthesis by NOS, if L-arginine levels decrease or consumption of NO increases via cell-free plasma hemoglobin and ROS, then oxidative damage occurs, HbS denatures, and superoxide production increases. It was shown that iNOS inhibition significantly limits tissue ischemiareperfusion injury in the liver and kidneys [10][11]; however, inhibition of iNOS attenuated ischemiareperfusion injury in the rat heart [12], but not in the rat lung [13]. Increased iNOS expression was reported in the kidneys of transgenic mice [9], but Nath et al [14] reported the lack of iNOS upregulation in intrarenal vasculature and increased iNOS expression in the glomeruli and distal tubules of sickle mice.…”

“…Increased iNOS expression and a consequent increase in tissue nitrite and nitrate production have been observed in the kidneys and liver of SCD patients [8], mice [2,3,8,9], and pigs [4]. Additionally, it was shown that iNOS inhibition significantly limits tissue ischemia-reperfusion injury in the liver and kidneys [10,11]; however, inhibition of iNOS attenuated ischemia-reperfusion injury in the rat heart [12] and did not affect ischemia-reperfusion injury in the rat lung [13]. Increased levels of iNOS expression were shown in the kidneys of transgenic mice [9], but Nath et al [14] reported the lack of upregulation of iNOS in the intrarenal vasculature and increased expression of iNOS in the [15][16][17] and in vitro [18].…”

Potential Benefits of Peroxynitrite

“…Moreover, it is hypothesized that this molecule determines the role of NO in either physiologic vs pathologic processes [3], as many of the pathological effects of NO are mediated by PN [3,[6][7][8]. These pathologic effects of PN are discussed in excellent reviews elsewhere [3,[9][10][11][12][13][14][15][16][17][18][19].…”