s-nitro-n-acetylpenicillamine and Myocardial-Infarction

We examined the role of nitric oxide (NO) in ischemia-reperfused hearts. In an occlusion-reperfusion model of hypercholesterolemic rabbits, the extent of myocardial infarction was increased because of the activation of neutrophils, possibly due to the impaired production of NO in atherosclerotic coronary circulation. It was reversed by the addition of exogenous NO releaser, SNAP. In a hypoxia-reoxygenation model of cultured cardiac myocytes, NO produced by endogenous cardiac iNOS augmented myocyte injury after exposure to hypoxia-reoxygenation. Inhibition of glutathione peroxidase activity was suggested to be the mechanism of sensitization to oxidative stress after exposure to NO. Therefore, NO is supposed to play two roles in ischemia-reperfused hearts, i.e., cardioprotective effect through coronary circulation and cardiotoxic effect through direct action on cardiac myocytes.

Topics: Animals; Cells, Cultured; Coronary Artery Disease; Depression, Chemical; Glutathione Peroxidase; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Nitric Oxide; Oxidative Stress; Penicillamine; Rabbits

To examine the inhibition of nitric oxide (NO) synthesis during ischemic preconditioning (IP) upon the induction of heat-shock protein 72 (HSP72) and the size-limiting effect of the second window of protection on infarction.. Rabbits were subjected to either 4 cycles of 5-min long coronary artery occlusion separated by 10 min of reperfusion, or a sham operation. During this procedure, we administered 10 mg/kg of N(G)-nitro-L-arginine methyl ester (L-NAME, an inhibitor of NO synthase) intravenously 5 min before IP followed by its continuous infusion (1.5 mg/kg/min). Twenty-four hours after IP or the sham operation, the hearts were rapidly excised for assay of HSP72 expression or were subjected to 30 min of coronary artery occlusion followed by 120 min of reperfusion, at which point infarct size (IS) was measured.. Twenty-four hours after IP or the sham operation, there was no difference in heart rate or mean arterial pressure between the groups. Immunoblotting revealed an increase in HSP72 protein levels in the IP group, which was blocked by L-NAME. IS in the IP rabbits was reduced compared with controls (29.8 +/- 3.7% vs. 50.8 +/- 4.3%, P < 0.01). IS in the IP rabbits was elevated as a result of L-NAME treatment (46.0 +/- 5.1%). Administration of L-arginine reversed the effects of L-NAME on the induction of HSP72 and IS (33.5 +/- 4.0%). The intravenous administration of S-nitroso-N-acetylpenicillamine (an NO donor, 15 microg/kg/min) over 20 min increased the induction of HSP72 and reduced IS (31.3 +/- 5.7%, P < 0.01 vs. control) 24 h later.. These findings suggest that NO may be involved in the induction of HSP72 and the opening of the second window of protection of IP.

Topics: Animals; Heat-Shock Proteins; Hemodynamics; HSP72 Heat-Shock Proteins; Ischemic Preconditioning, Myocardial; Male; Myocardial Infarction; Nitric Oxide; Penicillamine; Rabbits

Administration of nitric oxide (NO) donors during ischemia and reperfusion protects from myocardial injury. However, whether administration of an NO donor during a brief period prior to ischemia protects the myocardium and the endothelium against ischemia-reperfusion injury in vivo is unknown. To study this possibility anesthetized pigs were subjected to 45-min ligation of the left anterior descending coronary artery (LAD) followed by 4h of reperfusion. In initial dose-finding experiments, vehicle or three different doses of the NO donor S-nitroso-N-acetyl-D,L-penicillamin (SNAP; 0.1; 0.5; 2.5 micromol) were infused into the LAD for 3 min starting 13 min during ischemia. Only the 0.5 micromol dose of SNAP reduced infarct size (from 85+/-3% of the area at risk in the vehicle group to 63+/-3% in the SNAP-treated group; p<0.01). There were no significant differences in hemodynamics in the vehicle and SNAP groups during ischemia-reperfusion. Endothelium-dependent dilatation of coronary microvasculature induced by substance P was larger in the SNAP group than in the vehicle group. Myeloperoxidase activity was lower in the ischemic/reperfused myocardial area of pigs given SNAP (4.97+/-0.61 U/g) than in vehicle-treated pigs (8.45+/-0.25 U/g; p<0.05). It is concluded that intracoronary administration of the NO donor SNAP for a brief period before ischemia reduces infarct size, attenuates neutrophil accumulation, and improves endothelial function. These results suggest that NO exerts a classic preconditioning-like protection against ischemia-reperfusion injury in vivo in a narrow concentration range.

Topics: Animals; Cardiotonic Agents; Coronary Circulation; Dose-Response Relationship, Drug; Endothelium, Vascular; Hemodynamics; Myocardial Infarction; Myocardial Reperfusion Injury; Nitric Oxide; Nitric Oxide Donors; Penicillamine; Peroxidase; Swine

Nitric oxide (NO) has been reported to play an important role in the late phase of ischemic preconditioning (PC) in the rabbit heart. However, the role of NO in the early phase of ischemic PC ("classical PC") is controversial. Accordingly, the present study was designed to determine whether NO contributes to the cardioprotective effect of classical PC in rabbits. Isolated hearts experienced 30 min of regional ischemia followed by 120 min of reperfusion. Infarct size was measured with triphenyltetrazolium chloride. In control hearts infarction was 30.2+/-3.3% of the risk zone. PC with 5 min of global ischemia and 10 min of reperfusion reduced infarct size to 10.2+/-2.4% (P<0.05). Perfusion with 2 microm S-nitroso-N-acetylpenicillamine (SNAP), a NO donor, in lieu of ischemia mimicked PC (4.4+/-1.9% infarction, P<0.01 v control). To determine whether this protection was dependent on either protein kinase C (PKC) as has previously been demonstrated for classical PC or free radicals known to be produced during exogenous NO administration, chelerythrine (5 microm), a PKC inhibitor, or N-(2-mercaptopropionyl)-glycine (300 microm), a free radical scavenger, was administered with or shortly after SNAP. Neither drug had any independent effect on infarct size, and each blocked SNAP's cardioprotection (31.0+/-5.1 and 25.7+/-5.2% infarction, resp.). N(omega)-nitro- L -arginine methyl ester (L -NAME, 100 microm), a NO synthase inhibitor, failed to block the cardioprotection from the above ischemic PC protocol (9.5+/-2.8% infarction, P<0.05 v control). L -NAME alone had no effect on infarct size (30.6+/-2.7%). These results suggest that the beneficial effect of exogenous NO production during SNAP pretreatment is mediated by a protein kinase C-dependent pathway via MPG-sensitive oxidants. However, we were unable to show any contribution of endogenous NO to classical PC's protection in isolated rabbit hearts.

Topics: Animals; Antioxidants; Enzyme Inhibitors; Female; Free Radicals; Glycine; Heart; Hemodynamics; Ischemic Preconditioning, Myocardial; Male; Myocardial Infarction; Myocardium; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Donors; Penicillamine; Protein Kinase C; Rabbits; Sulfhydryl Compounds

It is unknown whether late preconditioning (PC) enhances the recovery of left ventricular (LV) function after a myocardial infarction. Thus 25 conscious rabbits were subjected to a 30-min coronary occlusion followed by 28 days of reperfusion after PC 24 h earlier with either ischemia or nitric oxide donor administration [S-nitroso-N-acetylpenicillamine (SNAP)]. The recovery of wall thickening (WTh) after reperfusion was significantly improved in the ischemic PC and SNAP PC groups compared with controls, both at rest and during dobutamine stress. Interestingly, neither ischemia- nor SNAP-induced late PC attenuated myocardial stunning from day 1 through day 14. Infarct size was smaller in the ischemic PC and SNAP PC groups compared with controls. In all groups, WTh at 28 days was positively and linearly related to the percentage of viable tissue in the region underlying the ultrasonic crystal (r = 0.90), indicating that the improvement in LV function after both ischemia-induced and NO donor-induced late PC can be fully explained by the reduction in infarct size; a separate effect of late PC on LV remodeling or LV contractility need not be invoked. In conclusion, in conscious rabbits late PC, induced either by ischemia or pharmacologically, not only limits infarct size but also enhances the recovery of LV function after myocardial infarction. This finding has important clinical implications and provides triphenyltetrazolium chloride-independent evidence that late PC limits myocellular death after sustained ischemia.

Topics: Animals; Consciousness; Dobutamine; Dose-Response Relationship, Drug; Electrocardiography; Hemodynamics; Ischemic Preconditioning, Myocardial; Male; Muscle Contraction; Myocardial Infarction; Myocardium; Nitric Oxide Donors; Penicillamine; Rabbits; Recovery of Function; Systole; Ventricular Function, Left

Although isoform-selective translocation of protein kinase C (PKC) epsilon appears to play an important role in the late phase of ischemic preconditioning (PC), the mechanism(s) responsible for such translocation remains unclear. Furthermore, the signaling pathway that leads to the development of late PC after exogenous administration of NO in the absence of ischemia (NO donor-induced late PC) is unknown. In the present study we tested the hypothesis that NO activates PKC and that this is the mechanism for the development of both ischemia-induced and NO donor-induced late PC. A total of 95 chronically instrumented, conscious rabbits were used. In rabbits subjected to ischemic PC (six 4-minute occlusion/4-minute reperfusion cycles), administration of the NO synthase inhibitor Nomega-nitro-L-arginine (group III), at doses previously shown to block the development of late PC, completely blocked the ischemic PC-induced translocation of PKCepsilon but not of PKCeta, indicating that increased formation of NO is an essential mechanism whereby brief ischemia activates the epsilon isoform of PKC. Conversely, a translocation of PKCepsilon and -eta quantitatively similar to that induced by ischemic PC could be reproduced pharmacologically with the administration of 2 structurally unrelated NO donors, diethylenetriamine/NO (DETA/NO) and S-nitroso-N-acetylpenicillamine (SNAP), at doses previously shown to elicit a late PC effect. The particulate fraction of PKCepsilon increased from 35+/-2% of total in the control group (group I) to 60+/-1% after ischemic PC (group II) (P<0.05), to 54+/-2% after SNAP (group IV) (P<0.05) and to 52+/-2% after DETA/NO (group V) (P<0.05). The particulate fraction of PKCeta rose from 66+/-5% in the control group to 86+/-3% after ischemic PC (P<0.05), to 88+/-2% after SNAP (P<0.05) and to 85+/-1% after DETA/NO (P<0.05). Neither ischemic PC nor NO donors had any appreciable effect on the subcellular distribution of PKCalpha, -beta1, -beta2, -gamma, -delta, - micro, or -iota/lambda; on total PKC activity; or on the subcellular distribution of total PKC activity. Thus, the effects of SNAP and DETA/NO on PKC closely resembled those of ischemic PC. The DETA/NO-induced translocation of PKCepsilon (but not that of PKCeta) was completely prevented by the administration of the PKC inhibitor chelerythrine at a dose of 5 mg/kg (group VI) (particulate fraction of PKCepsilon, 38+/-4% of total, P<0.05 versus group V; particulate fraction of PKCeta, 79+/-

Topics: Alkaloids; Animals; Benzophenanthridines; Enzyme Activation; Enzyme Inhibitors; Hemodynamics; Ischemic Preconditioning, Myocardial; Isoenzymes; Male; Myocardial Infarction; Myocardial Stunning; Myocardium; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitroarginine; Penicillamine; Phenanthridines; Polyamines; Protein Kinase C; Rabbits; Subcellular Fractions

Myocardial ischaemia followed by reperfusion (I/R) is associated with impaired endothelial function including diminished release and/or effects of nitric oxide (NO) which may contribute to the development of I/R injury. The aim of the present study was to investigate the role of the L-arginine/NO pathway in myocardial I/R injury. In isolated rat hearts subjected to global ischaemia followed by reperfusion L-arginine and the NO donor S-nitroso-N-acetyl-D,L-penicillamine (SNAP), but not D-arginine, significantly enhanced the recoveries of mycardial performance and coronary flow, and reduced the area of no-reflow and creatine kinase outflow. The NO synthase inhibitor NG-nitro-L-arginine (L-NNA) abolished the protective effects of L-arginine. Endothelium-dependent vasodilatation after I/R was preserved in L-arginine treated but not in vehicle hearts. Following I/R Ca2+-dependent NO synthase activity was reduced by 90% in comparison with non-ischaemic hearts. L-arginine but not D-arginine significantly increased NO synthase activity. In anaesthetized pigs, L-arginine given by local coronary venous retroinfusion reduced myocardial infarct size induced by 45 min of coronary artery ligation and 4 h of reperfusion to 35% of the area at risk from 76% in controls. The protective effect of L-arginine was blocked by L-NNA. Acetylcholine-induced coronary vasodilatation following I/R was attenuated in controls but not in L-arginine treated pigs. It is concluded that L-arginine or the NO donor SNAP reduces I/R-induced myocardial and endothelial injury. The protective effect of L-arginine seems to be mediated through maintained production of NO by preserving the function of Ca2+-dependent NO synthase in the heart.

Topics: Animals; Arginine; Coronary Circulation; Creatine Kinase; Enzyme Inhibitors; Heart; Hemodynamics; In Vitro Techniques; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Nitric Oxide; Nitric Oxide Synthase; Nitric Oxide Synthase Type III; Nitroarginine; Penicillamine; Perfusion; Rats; Rats, Sprague-Dawley; Swine