norbinaltorphimine and Myocardial-Ischemia

To observe the effects of κ-opioid receptor agonist U50, 488H on myocardial ischemia and reperfusion injury and related mechanism.. Rats were randomly divided into sham operation, myocardial ischemia and reperfusion(I/R, 30 min ischemia followed by 120 min reperfusion), and MI/R+U50, 488H (1.5 mg/kg) and I/R+U50, 488H+ selective κ-opioid receptor antagonist Nor-BNI (2 mg/kg, n = 8 each). The infarction size and the incidence of ventricular arrhythmias were observed.Real-time PCR and DAB staining were used to define the myocardium Toll-like receptor 4(TLR4) expression. Myeloperoxidase level, TNF-α induction and the expression of NF-κB were also examined in rats.. After I/R, the expressions of myocardial TLR4 and NF-κB increased significantly both in ischemia area and area at risk. Compared with I/R, κ-opioid receptor stimulation with U50, 488H significantly attenuated the expressions of TLR4 and NF-κB and reduced myeloperoxidase (MPO) levels, myocardial TNF-α production, myocardial infarct sizes and the incidence of ventricular arrhythmias and arrhythmia score (2.9 ± 0.7 vs. 4.4 ± 0.9, P < 0.05) , above effects of U50, 488H were partly abolished by co-treatment with Nor-BNI.. These data provide evidence for the first time that κ-opioid receptor stimulation could attenuate myocardial I/R injury via downregulating TLR4/NF-κB signaling in rats.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Arrhythmias, Cardiac; Brugada Syndrome; Cardiac Conduction System Disease; Coronary Artery Disease; Down-Regulation; Heart Conduction System; Myocardial Infarction; Myocardial Ischemia; Myocardium; Naltrexone; NF-kappa B; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Reperfusion Injury; Signal Transduction; Toll-Like Receptor 4; Tumor Necrosis Factor-alpha

Evidence has indicated U50,488H, a selective κ-opioid receptor (κ-OR) agonist, administered before ischemia attenuates apoptosis and infarction during ischemia and reperfusion (I/R). However, it remains unclear whether U50,488H postconditioning reduces apoptosis during I/R. This study was designed, therefore, to test the hypothesis that U50,488H administered at the onset of reperfusion inhibits cardiomyocyte apoptosis and to investigate the underlying mechanisms.. Male Sprague-Dawley rats were subjected to myocardial ischemia and reperfusion(MI/R) and were randomized to receive either vehicle, U50,488H, U50,488H plus Nor-BNI, a selective κ-OR antagonist, U50,488H plus wortmannin, a specific inhibitor of phosphoinositide 3'-kinase (PI3K), or U50,488H plus L-NAME, a nitric oxide synthase inhibitor (NOS inhibitor), immediately prior to reperfusion. In vitro study was performed on cultured neonatal cardiomyocytes subjected to simulated ischemia/reperfusion.. Treatment with U50,488H resulted in increases in Akt and endothelial nitric oxide synthase (eNOS) phosphorylation with secondary NO production both in vivo and in vitro and these effect were completely blocked by wortmannin and specific Akt inhibitor(AI). L-NAME treatment had no effect on Akt and eNOS phosphorylation; but, significantly reduced NO production. Moreover, treatment with U50,488H markedly reduced myocardial apoptotic death. Treatment with wortmannin and specific Akt inhibitor abolished the anti-apoptotic effect of U50,488H. L-NAME also significantly attenuated the anti-apoptotic effect of U50,488H.. These results demonstrate that U50,488H administered immediately prior to reperfusion increases Akt phosphorylation through a PI3-kinase-dependent mechanism and reduces postischemic myocardial apoptosis. Phosphorylation of eNOS with secondary NO production contribute significantly to the anti-apoptotic effect of U50,488H postconditioning.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics, Non-Narcotic; Androstadienes; Animals; Apoptosis; Cardiotonic Agents; Male; Myocardial Ischemia; Myocardial Reperfusion Injury; Naltrexone; Narcotic Antagonists; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Phosphoinositide-3 Kinase Inhibitors; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Wortmannin

To determine the effect of activation of lambda-opioid receptor with U50, 488H, a selective kappa-opioid receptor agonist, on the changes in electrical coupling during prolonged ischemia and to explore the possible mechanism.. The isolated rat heart was perfused in a Langendorff apparatus. The effect of U50, 488H on electrical coupling parameters including onset of uncoupling, plateau time, slope and fold increase in r(t) was observed in isolated perfused rat heart subjected to global no-flow ischemia. The effect of U50, 488H on connexin 43 (Cx43) expression of ventricular muscle during ischemia was determined by immunohistochemistry.. In the prolonged ischemia model, U50, 488H concentration dependently delayed the onset of uncoupling, increased time to plateau, and decreased the maximal rate of uncoupling during ischemia. The effect of U50, 488H on electrical uncoupling parameters during ischemia was abolished by a selective kappa-opioid receptor antagonist nor-BNI or a PKC inhibitor chelerythrine. The amount of Cx43 immunoreactive signal in ventricular muscle was greatly reduced after ischemia. U50, 488H markedly increased Cx43 expression during ischemia and its effect was also attenuated by nor-BNI or chelerythrine.. These results demonstrated that U50, 488H delayed the onset of uncoupling and plateau time, decreased the maximal rate of uncoupling and increased Cx43 expression of ventricular muscle during ischemia, and these effects of U50, 488H were mediated by kappa-opioid receptor, in which activation of PKC was involved. The effect of U50, 488H on electrical coupling during ischemia was probably correlated with preservation of Cx43 in cardiac muscle.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Benzophenanthridines; Connexin 43; Female; Heart; In Vitro Techniques; Myocardial Ischemia; Myocardium; Naltrexone; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Signal Transduction

During myocardial ischemia, the cranial cervical spinal cord (C1-C2) modulates the central processing of the cardiac nociceptive signal. This study was done to determine 1) whether C2 SCS-induced release of an analgesic neuropeptide in the dorsal horn of the thoracic (T4) spinal cord; 2) if one of the sources of this analgesic peptide was cervical propriospinal neurons, and 3) if chemical inactivation of C2 neurons altered local T4 substance P (SP) release during concurrent C2 SCS and cardiac ischemia. Ischemia was induced by intermittent occlusion of the left anterior descending coronary artery (CoAO) in urethane-anesthetized Sprague-Dawley rats. Release of dynorphin A (1-13), (DYN) and SP was determined using antibody-coated microprobes inserted into T4. SCS alone induced DYN release from laminae I-V in T4, and this release was maintained during CoAO. C2 injection of the excitotoxin, ibotenic acid, prior to SCS, inhibited T4 DYN release during SCS and ischemia; it also reversed the inhibition of SP release from T4 dorsal laminae during C2 SCS and CoAO. Injection of the kappa-opioid antagonist, nor-binaltorphimine, into T4 also allowed an increased SP release during SCS and CoAO. CoAO increased the number of Fos-positive neurons in T4 dorsal horns but not in the intermediolateral columns (IML), while SCS (either alone or during CoAO) minimized this dorsal horn response to CoAO alone, while inducing T4 IML neuronal recruitment. These results suggest that activation of cervical propriospinal pathways induces DYN release in the thoracic spinal cord, thereby modulating nociceptive signals from the ischemic heart.

Topics: Animals; Brain Stem; Coronary Vessels; Dynorphins; Electric Stimulation; Excitatory Amino Acid Agonists; Ibotenic Acid; Image Processing, Computer-Assisted; Immunohistochemistry; Male; Myocardial Ischemia; Naltrexone; Narcotic Antagonists; Neural Pathways; Neurons; Posterior Horn Cells; Proto-Oncogene Proteins c-fos; Rats; Rats, Sprague-Dawley; Spinal Cord; Substance P

To determine whether activation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical uncoupling during prolonged ischemia and whether these changes in electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation, and to explore the possible mechanism.. (1) To observe the effect of U50,488H (10(-7), 10(-6), 3 x10(-6) and 10(-5) mol/L), a selective kappa-opioid receptor agonist, or with a selective kappa-opioid receptor antagonist nor-BNI (5 x 10(-6) mol/L), or with a mitochondrial K(ATP) channel inhibitor 5-HD on myocardium during ischemia/reperfusion in isolated perfused rat heart. Parameters of measurements include hemodynamic data, formazan content, heart rate, coronary flow, and lactate dehydrogenase (LDH). (2) To examine the effect of U50,488H of different concentration on electrical coupling parameters (including onset of uncoupling, plateau time, slope, and fold increase in r1) during 70 min myocardial ischemia in isolated perfused rat heart.. (1) Pretreatment with U50,488H concentration dependently increased formazan content and reduced LDH release induced by 30 min of ischemia and 120 min of reperfusion. (2) The onset of electrical uncoupling and plateau time during prolonged ischemia was delayed by kappa-opioid receptor activation with U50,488H. (3) Linear regression analysis shown that the increase in formazan content and decrease in LDH release produced by kappa-opioid receptor activation was associated with delayed electrical uncoupling during prolonged ischemia. (4) The effects of U50,488H on formazan content, LDH release and on electrical coupling were abolished by nor-BNI, or 5-HD.. This results demonstrate that the onset of electrical uncoupling during prolonged ischemia is delayed by kappa-opioid receptor activation with a selective kappa-opioid receptor agonist U50,488H, and that delayed electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation with U50,488H. These effects of kappa-opioid receptor activation with U50,488H are mediated by mitochondrial K(ATP) channels.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Antihypertensive Agents; Heart; In Vitro Techniques; Male; Myocardial Ischemia; Myocardium; Naltrexone; Potassium Channels; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa

Pharmacological preconditioning with kappa-opioid receptor agonists is proarrhythmic and exerts antipreconditioning effects in rats. In swine, it is unknown whether kappa-opioid receptor stimulation plays a role in pharmacological preconditioning. Swine were preconditioned with 1) saline (controls), 2) [d-Ala(2),d-Leu(5)]enkephalin (DADLE), 3) morphine, 4) pentazocine, 5) norbinaltorphimine (nor-BNI), 6) DADLE + nor-BNI, 7) morphine + nor-BNI, or 8) pentazocine + nor-BNI before occlusion (45 min) and reperfusion (180 min) of the left anterior descending coronary artery. Infarct size to area at risk (IS), regional (systolic shortening) and global (pressures and flows) myocardial function, and arrhythmia occurrence were assessed. Only DADLE + nor-BNI preconditioning significantly decreased infarct size compared with controls (47 +/- 13 vs. 65 +/- 5%, P < 0.05); morphine preconditioning was not cardioprotective with or without kappa-opioid receptor blockade (nor-BNI). DADLE preconditioning significantly increased ischemia-induced arrhythmias relative to controls, whereas pentazocine-preconditioned animals (n = 2) experienced intractable ventricular fibrillation during ischemia. kappa-Opioid receptor blockade with DADLE or pentazocine preconditioning alleviated proarrhythmic effects. These results suggest that kappa-opioid receptor activation during pharmacological preconditioning is proarrhythmic in swine.

Topics: Animals; Arrhythmias, Cardiac; Coronary Circulation; Enkephalin, Leucine-2-Alanine; Hemodynamics; Ischemic Preconditioning, Myocardial; Morphine; Myocardial Infarction; Myocardial Ischemia; Naltrexone; Narcotic Antagonists; Narcotics; Pentazocine; Receptors, Opioid, kappa; Swine

To test the hypothesis that heat-shock proteins (HSPs) mediate delayed cardioprotection of prior kappa-opioid receptor (kappa-OR) stimulation, we first correlated cellular injury and viability with the expression of HSP70s in isolated rat ventricular myocytes subjected to prior kappa-OR stimulation with the selective agonist trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide (U-50488H) and delayed lethal simulated ischemia (LSI). Cell injury and viability were indicated by lactate dehydrogenase release and trypan blue exclusion, respectively. The reduced injury and increased viability after pretreatment with U-50488H were concentration dependent and correlated directly with the expression of both stress-inducible (HSP70) and constitutive (HSC70) proteins. The effects mimic those with metabolic inhibition preconditioning (MIP). The cardioprotection against LSI by pretreatment with U-50488H and MIP was abolished and antagonized, respectively, via blockade of the kappa-OR by its selective antagonist, nor-binaltorphimine. We also found that blockade of the production of HSP70 but not HSC70 blocked the inhibitory effect of pretreatment with U-50488H on injury and viability. These observations provide evidence that stress-inducible HSP70 mediates delayed cardioprotection of prior kappa-OR stimulation.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Animals; Heart; Heart Ventricles; HSP70 Heat-Shock Proteins; Ischemic Preconditioning, Myocardial; L-Lactate Dehydrogenase; Male; Myocardial Ischemia; Myocardium; Naltrexone; Narcotic Antagonists; Oligonucleotides, Antisense; Protective Agents; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa

To determine whether opioid receptors (ORs) are involved in the delayed cardioprotection of ischemic preconditioning (IP), the effect of severe metabolic inhibition (MI) with a glucose-free buffer that contained sodium cyanide and 2-deoxy-D-glucose on the viability of isolated rat ventricular myocytes was first determined 20 hours after preconditioning with a sublethal metabolic inhibition (MIP) with a glucose-free buffer that contained 2-deoxy-D-glucose and lactate for 30 minutes in the presence of OR antagonists. With the use of trypan blue exclusion as an index of cell viability, severe MI killed >60% of the cells and the value increased significantly after MIP. In the presence of 5x10(-6) mol/L nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, but not 5x10(-6) mol/L CTOP, a selective mu-OR antagonist, or 5x10(-6) mol/L naltrindole, a selective delta-OR antagonist, the cardioprotection of MIP was significantly attenuated. To verify the role of kappa-OR, we studied the effects of severe MI after pretreatment with the kappa-OR agonist U50,488H (UP) for 30 minutes. U50,488H at 3x10(-6) to 1x10(-4) mol/L increased cell viability concentration-dependently with an EC50 of 3.311x10(-6) mol/L. In the presence of 5x10(-6) nor-BNI, the cardioprotection of UP (3x10(-5) mol/L) was blocked. A time course study showed that UP-induced cardioprotection occurred in 2 windows: the first occurred approximately 1 hour later and the other occurred 16 to 20 hours later. Additional studies on cell contraction and intracellular Ca2+ ([Ca2+]i) revealed that both UP and MIP attenuated the inhibitory effects of severe MI on contractility and electrically induced [Ca2+]i transient in single ventricular myocytes. On blockade of protein kinase C, the delayed cardioprotections of UP and MIP were significantly attenuated. In conclusion, the results of the present study have provided evidence that kappa-OR mediates the cardioprotection of MIP, which may involve protein kinase C and [Ca2+]i.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Analgesics, Non-Narcotic; Animals; Calcium; Cell Survival; Electrophysiology; Energy Metabolism; Heart Ventricles; In Vitro Techniques; Ischemic Preconditioning, Myocardial; Membrane Potentials; Muscle Fibers, Skeletal; Myocardial Contraction; Myocardial Ischemia; Myocardium; Naltrexone; Narcotic Antagonists; Protein Kinase C; Rats; Rats, Sprague-Dawley; Receptors, Opioid, kappa; Trypan Blue