Apoptosis contributes to myocardial ischemia/reperfusion (MI/R) injury, and both thioredoxin (Trx) and nitric oxide have been shown to exert antiapoptotic effects in vitro . Recent evidence suggests that this particular action of Trx requires S-nitrosation at Cys-69. The present study sought to investigate whether or not exogenously applied Trx reduces MI/R injury in vivo and to which extent this effect depends on S-nitrosation. Adult mice were subjected to 30 min of MI and treated with either vehicle or human Trx (hTrx, 2 mg/kg, i.p.) 10 min before reperfusion. Native hTrx was incorporated into myocardial tissue as shown by immunostaining, and reduced MI/R injury as evidenced by decreased terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, DNA fragmentation, caspase-3 activity, and infarct size. When hTrx was partially S-nitrosated by preincubation with S -nitrosoglutathione, its cardioprotective effect was markedly enhanced. Treatment with hTrx significantly reduced p38 mitogen-activated protein kinase (MAPK) activity, and this effect was also potentiated by S-nitrosation. To further address the role of S-nitrosation for the overall antiapoptotic effect to Trx, the action of Escherichia coli Trx (eTrx) was investigated in the same model. Whereas eTrx inhibited MI/R-induced apoptosis to a degree similar to hTrx, S-nitrosation of this protein, which lacks Cys-69, failed to further enhance its antiapoptotic action. Collectively, our results demonstrate that systemically applied Trx is taken up by the myocardium to exert potent cardioprotective effects in vivo , offering interesting therapeutic avenues. In the case of hTrx, these effects are further potentiated by S-nitrosation, but this posttranslational modification is not essential for protection.

Background-Omi/HtrA2 is a proapoptotic mitochondrial serine protease involved in caspase-dependent as well as caspase-independent cell death. However, the role of Omi/HtrA2 in the apoptotic cell death that occurs in vivo under pathological conditions remains unknown. The present study was designed to investigate whether Omi/HtrA2 plays an important role in postischemic myocardial apoptosis. Methods and Results-Male adult mice were subjected to 30 minutes of myocardial ischemia followed by reperfusion and treated with vehicle or ucf-101, a novel and specific Omi/HtrA2 inhibitor, 10 minutes before reperfusion. Myocardial ischemia/reperfusion significantly increased cytosolic Omi/HtrA2 content and markedly increased apoptosis. Treatment with ucf-101 exerted significant cardioprotective effects, as evidenced by less terminal dUTP nick end-labeling staining, a lower incidence of DNA ladder fragmentation, and smaller infarct size. Furthermore, treatment with ucf-101 before reperfusion attenuated X-linked inhibitor of apoptosis protein degradation and inhibited caspase-9 and caspase-3 activities. Conclusion-Taken

Background-Peroxisome proliferator-activated receptor (PPAR) signaling pathways have been reported to exert anti-inflammatory effects and attenuate atherosclerosis formation. However, the mechanisms responsible for their anti-inflammatory and antiatherosclerotic effects remain largely unknown. The present study tested the hypothesis that a PPAR␥ agonist may exert significant endothelial protection by antioxidative and antinitrative effects. Methods and Results-Male New Zealand White rabbits were randomized to receive a normal (control) or a high-cholesterol diet and treated with vehicle or rosiglitazone (a PPAR␥ agonist) 3 mg · kg Ϫ1 · d Ϫ1 for 5 weeks beginning 3 weeks after the high-cholesterol diet. At the end of 8 weeks of a high-cholesterol diet, the rabbits were killed, and the carotid arteries were isolated. Bioactive nitric oxide was determined functionally (endothelium-dependent vasodilatation) and biochemically (the phosphorylation of vasodilator-stimulated phosphoprotein, or P-VASP). Vascular superoxide production, PPAR␥, gp91 phox , and inducible nitric oxide synthase (iNOS) expression, and vascular ONOO