Role of S-nitrosothiol transport in the cardioprotective effects of S-nitrosocysteine in rat hearts.
ABSTRACT The objective of this study was to determine if prior exposure of rat hearts to S-nitrosocysteine (CysNO) was able to provide protection against reperfusion injury. We probed NO release using the extracellular NO scavenger oxyhemoglobin (oxyHb), and we examined the involvement of the amino acid transport system L (L-AT), a known transporter of CysNO, using the L-AT competitor, L-leucine (L-Leu). Isolated (9- to 12-week-old Wistar male) rat hearts (six to eight per group) were perfused with CysNO (10 microM) for 30 min with or without the L-AT competitor L-Leu (1 mM) before 30 min of ischemia. Cardiac function was assessed before, during, and after treatment and during 120 min of reperfusion after ischemia. Functional recovery (rate-pressure product) was significantly improved in the CysNO group compared to hearts in the CysNO+L-Leu group and the control group (p<0.05). Necrosis, measured by triphenyltetrazolium chloride staining, was significantly reduced in CysNO hearts (p<0.05) and this improvement was reversed by L-Leu. The NO scavenger oxyHb (20 microM) was perfused either concomitant with CysNO or just before ischemia. In neither case did oxyHb affect the cardioprotection afforded by CysNO. OxyHb alone, given in either time window, did not alter the course of ischemia-reperfusion injury. When nitrite was used in place of CysNO, no protective effects were observed. Perfusion with CysNO increased tissue S-nitrosothiol (RSNO) levels from an unmeasurable background to a value of about 15.7+/-4.1 pmol RSNO/mg protein, as measured by triiodide-based chemiluminescence in the presence and absence of mercury(II) chloride. In the presence of L-Leu, this value dropped to 0.4+/-0.3 pmol RSNO/mg protein. This study demonstrates that exposure to CysNO before ischemia increases tissue S-nitrosothiol levels, improves postischemic contractile dysfunction, and attenuates necrosis. The mechanism of cardioprotection requires the uptake of CysNO via the L-AT and does not seem to involve NO release either during CysNO exposure or during ischemia. This suggests that the protective effects of CysNO are mediated through the posttranslational modification of cellular proteins through an NO-independent transnitrosation mechanism.
SourceAvailable from: Egeria Scoditti[Show abstract] [Hide abstract]
ABSTRACT: This review summarizes available evidence on the beneficial effects of inorganic nitrates and the monounsaturated fatty acid (MUFA) oleic acid, largely contained in Mediterranean diet, on blood pressure and coagulation activity.Inorganic nitrate. Normal vascular function requires NO production from the 1-arginine–NO synthase (NOS) pathway. This process is defective in conditions of local hypoxia, and here nitrite can substitute for 1-arginine–NOS derived NO. In this context, NO generation from the nitrate–nitrite–NO pathway mostly derived from green leafy vegetables appears to be an alternative source for NOS-dependent NO production, ensuring NO bioavailability also in situations when the endogenous 1-arginine/NO synthase pathway is dysfunctional or physiologically reduced in local hypoxic conditions.Olive oil and oleic acid. In addition to effects on lipoprotein metabolism and oxidation, the beneficial effects of oleic acid occur also on coagulation activity, namely on coagulation factor VII (FVII). Normally, a substantial increase of FVII coagulant activity (FVIIc) occurs within 2–3 h after a fatty meal and persists for several hours thereafter. When a background diet high in MUFA is consumed, a lower post-prandial increase of FVIIc takes place.Vascular Pharmacology 10/2014; 63(3). DOI:10.1016/j.vph.2014.10.001 · 4.62 Impact Factor
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ABSTRACT: Nitric oxide production by the endothelium is required for normal vascular homeostasis; however, in conditions of oxidative stress, interactions of nitric oxide with reactive oxygen species (ROS) are thought to underlie endothelial dysfunction. Beyond canonical nitric oxide signaling pathways, nitric oxide production results in the post-translational modification of protein thiols, termed S-nitrosation. The potential interplay between S-nitrosation and ROS remains poorly understood and is the focus of the current study. The effects of the S-nitrosating agent S-nitrosocysteine (CysNO) in combination with redox-cycling agents was examined in bovine aortic endothelial cells (BAEC). CysNO significantly impairs mitochondrial function and depletes the NADH/NAD(+) pool; however, these changes do not result in cell death. When faced with the additional stressor of a redox-cycling agent used to generate ROS, further loss of NAD(+) occurs, and cellular ATP pools are depleted. Cellular S-nitrosothiols also accumulate, and cell death is triggered. These data demonstrate that CysNO sensitizes endothelial cells to redox-cycling agent-dependent mitochondrial dysfunction and cell death and identify attenuated degradation of S-nitrosothiols as one potential mechanism for the enhanced cytotoxicity.01/2013; 1(1):1-7. DOI:10.1016/j.redox.2012.11.003
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ABSTRACT: Exercise promotes cardioprotection in both humans and animals not only by reducing risk factors associated with cardiovascular disease but by reducing myocardial infarction and improving survival following ischemia. This article will define the role that nitric oxide and β-adrenergic receptors play in mediating the cardioprotective effects of exercise in the setting of ischemia-reperfusion injury.Physiology 07/2013; 28(4):216-24. DOI:10.1152/physiol.00011.2013 · 5.65 Impact Factor