Coronary heart disease (CHD) remains the greatest killer in the Western world, and although the death rate from CHD has been falling, the current increased prevalence of major risk factors including obesity and diabetes, suggests it is likely that CHD incidence will increase over the next 20 years. In conjunction with preventive strategies, major advances in the treatment of acute coronary syndromes and myocardial infarction have occurred over the past 20 years. In particular the ability to rapidly restore blood flow to the myocardium during heart attack, using interventional cardiologic or thrombolytic approaches has been a major step forward. Nevertheless, while 'reperfusion' is a major therapeutic aim, the process of ischemia followed by reperfusion is often followed by the activation of an injurious cascade. While the pathogenesis of ischemia-reperfusion is not completely understood, there is considerable evidence implicating reactive oxygen species (ROS) as an initial cause of the injury. ROS formed during oxidative stress can initiate lipid peroxidation, oxidize proteins to inactive states and cause DNA strand breaks, all potentially damaging to normal cellular function. ROS have been shown to be generated following routine clinical procedures such as coronary bypass surgery and thrombolysis, due to the unavoidable episode of ischemia-reperfusion. Furthermore, they have been associated with poor cardiac recovery post-ischemia, with recent studies supporting a role for them in infarction, necrosis, apoptosis, arrhythmogenesis and endothelial dysfunction following ischemia-reperfusion. In normal physiological condition, ROS production is usually homeostatically controlled by endogenous free radical scavengers such as superoxide dismutase, catalase, and the glutathione peroxidase and thioredoxin reductase systems. Accordingly, targeting the generation of ROS with various antioxidants has been shown to reduce injury following oxidative stress, and improve recovery from ischemia-reperfusion injury. This review summarises the role of myocardial antioxidant enzymes in ischemia-reperfusion injury, particularly the glutathione peroxidase (GPX) and the thioredoxin reductase (TxnRed) systems. GPX and TxnRed are selenocysteine dependent enzymes, and their activity is known to be dependent upon an adequate supply of dietary selenium. Moreover, various studies suggest that the supply of selenium as a cofactor also regulates gene expression of these selenoproteins. As such, dietary selenium supplementation may provide a safe and convenient method for increasing antioxidant protection in aged individuals, particularly those at risk of ischemic heart disease, or in those undergoing clinical procedures involving transient periods of myocardial hypoxia.

We demonstrate that AGEs represent a potentially important cause of vascular dysfunction, linked to the induction of nitric oxide resistance. These findings also emphasize the deleterious and potentially additive effects of AGEs and hyperglycemia in diabetic vasculature.

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Background-Endothelial dysfunction because of reduced nitric oxide bioavailability is a key feature of essential hypertension. We have found that normotensive siblings of subjects with essential hypertension have impaired endothelial function accompanied by altered arginine metabolism. Methods and Results-We have identified a novel C/T polymorphism in the 3ЈUTR of the principal arginine transporter, solute carrier family 7 (cationic amino acid transporter, yϩ system), member 1 gene (SLC7A1). The minor T allele significantly attenuates reporter gene expression (PϽ0.01) and is impaired in its capacity to form DNA-protein complexes (PϽ0.05). In 278 hypertensive subjects the frequency of the T allele was 13.3% compared with 7.6% in 498 normotensive subjects (PϽ0.001). Moreover, the overall genotype distribution observed in hypertensives differed significantly from that in normotensives (PϽ0.001). To complement these studies, we generated an endothelial-specific transgenic mouse overexpressing L-arginine transporter SLC7A1. The Slc7A1 transgenic mice exhibited significantly enhanced responses to the endothelium-dependent vasodilator acetylcholine (Ϫlog EC 50 for wild-type versus Slc7A1 transgenic: 6.87Ϯ0.10 versus 7.56Ϯ0.13; PϽ0.001). This was accompanied by elevated production of nitric oxide by isolated aortic endothelial cells. Conclusions-The present study identifies a key, functionally active polymorphism in the 3ЈUTR of SLC7A1. As such, this polymorphism may account for the apparent link between altered endothelial function, L-arginine, and nitric oxide metabolism and predisposition to essential hypertension.

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Abstract-Endothelial dysfunction is a hallmark of cardiovascular disease, and the L-arginine:NO pathway plays a critical role in determining endothelial function. Recent studies suggest that smoking, a well-recognized risk factor for vascular disease, may interfere with L-arginine and NO metabolism; however, this remains poorly characterized. Accordingly, we performed a series of complementary in vivo and in vitro studies to elucidate the mechanism by which cigarette smoke adversely affects endothelial function. In current smokers, plasma levels of asymmetrical dimethyl-arginine (ADMA) were 80% higher (Pϭ0.01) than nonsmokers, whereas citrulline (17%; PϽ0.05) and N-hydroxy-L-arginine (34%; PϽ0.05) were significantly lower. Exposure to 10% cigarette smoke extract (CSE) significantly affected endothelial arginine metabolism with reductions in the intracellular content of citrulline (81%), N-hydroxy-L-arginine (57%), and arginine (23%), while increasing ADMA (129%). CSE significantly inhibited (38%) arginine uptake in conjunction with a 34% reduction in expression of the arginine transporter, CAT1. In conjunction with these studies, CSE significantly reduced the activity of eNOS and NO production by endothelial cells, while stimulating the production of reactive oxygen species. In conclusion, cigarette smoke adversely affects the endothelial L-arginine NO synthase pathway, resulting in reducing NO production and elevated oxidative stress. In conjunction, exposure to cigarette smoke increases ADMA concentration, the latter being a risk factor for cardiovascular disease. Key Words: smoking Ⅲ endothelium Ⅲ metabolism A therosclerotic coronary and cerebrovascular disease are leading causes of death and disability in the Western world, and cigarette smoking has been clearly identified as a risk factor for coronary artery disease (reviewed by Ambrose and Barua 1 ). In this context, measures of endothelial function have been associated with cardiovascular outcome, 2 and smoking has been widely associated with reduced endothelial function. 3 The endothelium plays a central role in the modulation of vascular tone, the inhibition of platelet aggregation and vascular smooth muscle proliferation, and a key participation in angiogenesis under appropriate conditions. NO is well recognized as playing a pivotal part in these endothelial properties, being produced by the endothelial isoform of NO from its preferred substrate L-arginine. In this context, provision of sufficient L-arginine is critical for the sustained production of NO supply, 4 mediated in endothelial cells (ECs) principally by the type 1 cationic amino acid transporter (CAT1). Previous studies indicate that deleterious actions of cigarette smoke on endothelial function could be mitigated by supplemental L-arginine; 5 however, to date, the precise basis for this interaction remains unclear. One explanation is that cigarette smoke exerts an inhibitory effect on components of the L-arginine:NO pathway to influence NO production. In addition, potential effects of cigar...

BACKGROUND AND PURPOSEAnnexin-A1 (ANX-A1) is an endogenous, glucocorticoid-regulated anti-inflammatory protein. The N-terminal-derived peptide Ac-ANX-A12-26 preserves cardiomyocyte viability, but the impact of ANX-A1-peptides on cardiac contractility is unknown. We now test the hypothesis that ANX-A1 preserves post-ischaemic recovery of left ventricular (LV) function. EXPERIMENTAL APPROACHAc-ANX-A12-26 was administered on reperfusion, to adult rat cardiomyocytes as well as hearts isolated from rats, wild-type mice and mice deficient in endogenous ANX-A1 (ANX-A1 -/-). Myocardial viability and recovery of LV function were determined. KEY RESULTSIschaemia-reperfusion markedly impaired both cardiomyocyte viability and recovery of LV function by 60%. Treatment with exogenous Ac-ANX-A12-26 at the onset of reperfusion prevented cardiomyocyte injury and significantly improved recovery of LV function, in both intact rat and wild-type mouse hearts. Ac-ANX-A12-26 cardioprotection was abolished by either formyl peptide receptor (FPR)-nonselective or FPR1-selective antagonists, Boc2 and cyclosporin H, but was relatively insensitive to the FPR2-selective antagonist QuinC7. ANX-A1-induced cardioprotection was associated with increased phosphorylation of the cell survival kinase Akt. ANX-A1-/-exaggerated impairment of post-ischaemic recovery of LV function, in addition to selective LV FPR1 down-regulation. CONCLUSIONS AND IMPLICATIONSThese data represent the first evidence that ANX-A1 affects myocardial function. Our findings suggest ANX-A1 is an endogenous regulator of post-ischaemic recovery of LV function. Furthermore, the ANX-A1-derived peptide Ac-ANX-A12-26 on reperfusion rescues LV function, probably via activation of FPR1. ANX-A1-based therapies may thus represent a novel clinical approach for the prevention and treatment of myocardial reperfusion injury.

The development of diabetic cardiomyopathy is a key contributor to heart failure and mortality in obesity and type 2 diabetes (T2D). Current therapeutic interventions for T2D have limited impact on the development of diabetic cardiomyopathy. Clearly, new therapies are urgently needed. A potential therapeutic target is protein kinase D (PKD), which is activated by metabolic insults and implicated in the regulation of cardiac metabolism, contractility and hypertrophy. We therefore hypothesised that PKD inhibition would enhance cardiac function in T2D mice. We first validated the obese and T2D db/db mouse as a model of early stage diabetic cardiomyopathy, which was characterised by both diastolic and systolic dysfunction, without overt alterations in left ventricular morphology. These functional characteristics were also associated with increased PKD2 phosphorylation in the fed state and a gene expression signature characteristic of PKD activation. Acute administration of the PKD inhibitor CID755673 to normal mice reduced both PKD1 and 2 phosphorylation in a time and dose-dependent manner. Chronic CID755673 administration to T2D db/db mice for two weeks reduced expression of the gene expression signature of PKD activation, enhanced indices of both diastolic and systolic left ventricular function and was associated with reduced heart weight. These alterations in cardiac function were independent of changes in glucose homeostasis, insulin action and body composition. These findings suggest that PKD inhibition could be an effective strategy to enhance heart function in obese and diabetic patients and provide an impetus for further mechanistic investigations into the role of PKD in diabetic cardiomyopathy.