Cardiomyocyte-Specific Overexpression of NO Synthase-3 Protects Against Myocardial Ischemia-Reperfusion Injury

Abstract

Objective-The protective effect of NO synthase-3 (eNOS)-derived NO in limiting myocardial ischemia-reperfusion (MI-R) injury is well established. We reported previously that systemic genetic overexpression of eNOS attenuates MI-R injury. The purpose of the current study was to investigate tissue-specific genetic overexpression of the human eNOS gene. Methods and Results-To accomplish this, we used 2 distinct murine models of transgenic overexpression, a cardiomyocyte-specific eNOS overexpresser (CS eNOS-Tg) under the control of the ␣-myosin heavy chain promoter, and a systemic eNOS transgenic mouse (SYS eNOS-Tg) under control of the native eNOS promoter with an upstream endothelial enhancer element. Mice were subjected to 30 or 45 minutes of left coronary artery ischemia and 24 or 72 hours of reperfusion. CS eNOS-Tg mice displayed significantly decreased infarct size beyond that of mice with systemic overexpression. Additionally, CS eNOS-Tg mice exhibited better preservation of cardiac function compared with SYS eNOS-Tg mice after myocardial infarction. Key Words: gene therapy Ⅲ myocardial infarction Ⅲ eNOS Ⅲ cardiomyocyte Ⅲ endothelial Ⅲ cardiac function Ⅲ blood pressure N itric oxide (NO) is a free-radical species generated by the enzyme endothelial NO synthase (eNOS). NO has been shown to play a prominent role in the maintenance of vascular homeostasis by acting as a vasodilator, 1-3 attenuating platelet 4 and leukocyte 5 adhesion, inhibiting vascular smooth muscle cell proliferation, 6 and possessing multiple other anti-inflammatory properties. eNOS is also present and functional in cardiac myocytes, 7 in which NO generation has been shown 8 -11 to modulate cardiac function. Conclusion-TheseIt is now well appreciated that NO can exert many beneficial effects in various cardiovascular disease states. NO has been shown to protect against myocardial ischemiareperfusion (MI-R) injury in a number of animal models. [12][13][14] These basic science observations have led to the recent translation of NO-based therapies to the clinic. The African American Heart Failure Trial found isosorbide dinitrate-hydralazine to significantly lower mortality rates in patients with class III and IV heart failure, prompting an early termination of the trial and introduction of isorbide dinitratehydralazine (BilDil) to the medicinal armament. 15 Additionally, a recent study of inhaled NO demonstrated acute hemodynamic improvements in patients with right ventricular myocardial infarction (MI) and cardiogenic shock. 16 In addition to direct NO therapy, the role of NO synthase-3 (eNOS) in MI-R has been studied extensively. Mice deficient in eNOS (eNOS Ϫ/Ϫ ) have increased myocardial injury after I-R, displaying significantly larger infarct size. 17,18 Conversely, augmenting eNOS function has proven to be very effective at reducing MI-R injury. Supplementation of the eNOS substrate L-arginine, has been shown 19,20 to reduce infarct size after MI-R injury. We reported previously 21 the protective effects of systemic, genetic eNOS overe...

The PI3K/Akt pathway mediates the protection of SO2 preconditioning against myocardial ischemia/reperfusion injury in rats

“…SO 2 preconditioning reduced the myocardial infarct size of rats with I/R We determined the infarct size using the Evans-TTC method to evaluate the direct effect of SO 2 preconditioning on myocardial I/R injury [17] . The area at risk was expressed as a ratio of AAR to VS (AAR/VS), and the area of the infarct size was expressed as a ratio of AI to AAR (AI/AAR).…”

“…The AAR, AI and ventricle size (VS) were assessed by a blinded observer using computer-assisted planimetry (NIH Image 1.57 software). The procedures for determining the AAR and AI were as previously described [17] .…”

Hydrogen sulfide cytoprotective signaling is endothelial nitric oxide synthase-nitric oxide dependent

“…Mice were subjected to 45 min of myocardial ischemia and 24 h of reperfusion. Surgical procedures were performed as described previously (45).…”

Exercise training improves functional post-ischemic recovery in senescent heart

“…However, the beneficial effects of endurance training on coronary flow could also result from a decrease in responsiveness to vasoconstrictive stimuli such as endothelin (Besse et al, 2001;Symons et al, 2000) and/or a coronary vascular remodeling such as angiogenesis (Brown, 2003;Linke et al, 2006;Iemitsu et al, 2006;Marini et al, 2008;Leosco et al, 2008). Moreover, increased eNOS myocardial content by endurance training could also improves the postischemic contractile function by cardiomyocyte-specific mechanisms (Jugdutt, 2002;Razavi et al, 2005 ;Elrod et al, 2006).…”