Seiji Matsuhisa

Angiotensin II type 1 receptor blocker preserves tolerance to ischemia-reperfusion injury in Dahl salt-sensitive rat heart.

Oxidative stress is involved in the tolerance to ischemia-reperfusion (I/R) injury. Because angiotensin II type 1 receptor blockers (ARBs) inhibit oxidative stress, there is concern that ARBs abolish the tolerance to I/R injury. Dahl salt-sensitive (DS) hypertensive and salt-resistant (DR) normotensive rats received an antioxidant, 2-mercaptopropionylglycine (MPG), or an ARB, losartan, for 7 days. Losartan and MPG significantly inhibited oxidative stress as determined by tissue malondialdehyde + 4-hydroxynoneal and increased expression of inducible nitric oxide synthase (iNOS) in the DS rat heart. However, losartan but not MPG activated endothelial nitric oxide synthase (eNOS) as assessed by phosphorylation of eNOS on Ser1177. Infarct size after 30-min left coronary artery occlusion followed by 2-h reperfusion was comparable between DS and DR rat hearts. Although MPG and losartan had no effect on infarct size in the DR rat heart, MPG but not losartan significantly increased infarct size in the DS rat heart. A selective iNOS inhibitor, 1400W, increased infarct size in the DS rat heart, but it had no effect on infarct size in the losartan-treated DS rat heart. However, a nonselective NOS inhibitor, Nomega-nitro-l-arginine methyl ester, increased infarct size in the losartan-treated DS rat heart. These results suggest that losartan preserves the tolerance to I/R injury by activating eNOS despite elimination of redox-sensitive upregulation of iNOS and iNOS-dependent cardioprotection in the DS rat heart.

N-acetylcysteine abolishes the protective effect of losartan against left ventricular remodeling in cardiomyopathy hamster.

Oxidative stress mediated by activation of angiotensin II type-1 receptor (AT(1)R) plays a crucial role in the progression of heart failure. We investigated the effect of N-acetylcysteine (NAC) and an AT(1)R blocker on oxidative stress and left ventricular (LV) remodeling in BIO14.6 cardiomyopathy hamsters. The cardiomyopathy hamsters were treated with NAC or the AT(1)R blocker losartan for 20 weeks. Although NAC and losartan inhibited oxidative stress and upregulation of iNOS in the cardiomyopathy hamster heart, only losartan inhibited LV chamber dilation, myocardial fibrosis, and LV dysfunction in the cardiomyopathy hamster. Co-treatment with NAC abolished the protective effect of losartan against LV remodeling associated with inhibition of phosphatidylinositol 3-kinase (PI3K)/Akt and eNOS activation. An iNOS inhibitor 1400W or a nonselective NOS inhibitor Nomega-nitro-L-arginine methyl ester (L-NAME) exacerbated LV remodeling in the cardiomyopathy hamster. However, L-NAME but not 1400W abrogated losartan-mediated inhibition of LV remodeling. These results suggest that redox-sensitive upregulation of iNOS plays a crucial role in preventing LV remodeling in the BIO14.6 cardiomyopathy hamster. Losartan inhibits LV remodeling by switching the cardioprotective mechanism from iNOS- to eNOS-dependence, but NAC abolishes the protective effect of losartan by inhibiting redox-sensitive activation of PI3K/Akt and eNOS in the cardiomyopathy hamster.

Addition of cilostazol to aspirin therapy for secondary prevention of cardiovascular and cerebrovascular disease in patients undergoing percutaneous coronary intervention: A randomized, open-label trial.

BACKGROUND Patients with established coronary artery disease are at increased risk for future ischemic events and require secondary prevention for systemic vascular disease. We performed a randomized clinical trial to evaluate the impact of cilostazol on cardiovascular and cerebrovascular disease in patients undergoing percutaneous coronary intervention. METHODS A total of 514 patients who had undergone coronary stent implantation >6 months previously and were thought to no longer need dual antiplatelet therapy with aspirin and a thienopyridine were randomly assigned to receive aspirin plus cilostazol therapy or aspirin therapy alone after discontinuation of thienopyridine therapy. The primary efficacy end point was a composite of all-cause death, myocardial infarction, stroke, or cardiovascular or cerebrovascular revascularization at 2 years after randomization. The main safety end point was major or minor bleeding, according to the Thrombolysis in Myocardial Infarction bleeding definition. RESULTS At 2 years, follow-up clinical data were available for 98.1% of patients. The primary efficacy end point occurred in 13.9% of the aspirin plus cilostazol group versus 22.1% of the aspirin-only group (hazard ratio 0.61, 95% CI 0.40-0.93, P = .021). The rate of major or minor bleeding was not significantly different between the aspirin plus cilostazol and aspirin-only groups (1.6% and 4.0%, respectively, hazard ratio 0.40, 95% CI 0.13-1.28, P = .12). CONCLUSIONS In patients who underwent coronary stent implantation, the addition of cilostazol to aspirin therapy was associated with lower rates of cardiovascular and cerebrovascular events at 2 years compared with aspirin monotherapy.