enkephalin--leucine-2-alanine and Myocardial-Ischemia

Effects of intravenous dalargin daily administered in a dose of 28 micrograms/kg during 7 days on hemodynamics, oxygen balance, lipid spectrum were studied in patients with coronary heart disease. The results of the treatment show that dalargin decreases incidence of anginal attacks, peripheral vascular resistance, venous tonicity, increases exercise tolerance, peripheral blood flow and venous flow. In addition, such treatment reduces oxygen consumption, levels of total cholesterol, triglycerides, low density lipoprotein cholesterol.

Topics: Adrenergic beta-Agonists; Anti-Arrhythmia Agents; Enkephalin, Leucine-2-Alanine; Enkephalins; Female; Hemodynamics; Humans; Injections, Intravenous; Lipoproteins; Male; Middle Aged; Myocardial Ischemia; Receptors, Opioid; Receptors, Opioid, mu

Previous studies have described the protective effects of DADLE on myocardial injury in sepsis. Recently, autophagy has been shown to be an innate defense mechanism in sepsis-related myocardial injury. However, whether DADLE has an pro-autophagic effect is yet to be elucidated. The present study aimed to investigate the effect of DADLE on the regulation of autophagy during sepsis.. Male mice were subjected to LPS or vehicle intraperitoneal injection. After LPS injection, mice received either DADLE, Naltrindole or vehicle. ELISA and JC-1 were used to evaluate the level cTnI and Mitochondrial membrane potential. Cardiac ultrastructural and autophagosomes were visualized by transmission electron microscopy. The relative protein levels were analyzed by Western blot.. The results showed that treatment with DADLE both immediately or 4 h after LPS intraperitoneal injection could improve the survival rate of mice with endotoxemic. DADLE could ease myocardium ultrastructure injury induced by LPS, this cardioprotective effect was also seen in increased MMP levels, and decreased cTnI levels. Through observation of transmission electron microscopy and Western blot we have discovered that the amount of autophagosome and the expression of autophagy related protein LC3II, Beclin1 were significantly increased with DADLE treatment. DADLE promoted LPS-induced autophagosome maturation as indicated by the increased LAMP-1 protein level and decreased SQSTM1/p62 protein level. The selective δ-opioid receptor antagonist Naltrindole play an opposite effects.. DADLE could improve the survival and protect myocardial dysfunction in mice with LPS-induced endotoxemia. This effect was related to the increase of autophagy.

Topics: Animals; Autophagy; Enkephalin, Leucine-2-Alanine; Injections, Intraperitoneal; Lipopolysaccharides; Male; Mice; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Myocardial Ischemia; Receptors, Opioid, delta

The aim of this study was to examine the hypothesis that delta-opioid receptor activation before ischemia suppresses gap junction (GJ) permeability by PKC-mediated connexin 43 (Cx43) modulation, which contributes to infarct size limitation afforded by the delta-opioid receptor activation. A delta-opioid receptor agonist, [D-Ala(2),D-Leu(5)]-enkephalin acetate (DADLE, 300 nM), was used in place of preconditioning (PC) ischemia to trigger PC mechanisms in rat hearts. GJ permeability during ischemia, which was assessed by Lucifer yellow, was reduced by DADLE to 47% of the control level, and this effect of DADLE was almost abolished by a PKC-epsilon inhibitor [PKC-epsilon translocation inhibitory peptide (PKC-epsilon-TIP)] but was not affected by a PKC-delta inhibitor (rottlerin). After DADLE infusion, PKC-epsilon, but not PKC-delta, was coimmunoprecipitated with Cx43, and the level of phosphorylation of Cx43 at a PKC-dependent site (Ser(368)) was significantly elevated during ischemia. DADLE reduced infarct size after 35 min of ischemia followed by 2 h of reperfusion by 69%, and PKC-epsilon-TIP and rottlerin eliminated 48% and 63%, respectively, of the infarct size-limiting effect of DADLE. Infusion of a GJ blocker, heptanol, before reperfusion reduced infarct size by 36%, and this protection was not enhanced by preischemic infusion of rottlerin + DADLE, which allows PKC-epsilon activation by DADLE. These results suggest that phosphorylation of Cx43 by PKC-epsilon plays a crucial role in delta-opioid-induced suppression of GJ permeability in ischemic myocardium and that this modulation of the GJ is possibly an adjunct mechanism of infarct size limitation afforded by preischemic delta-opioid receptor activation.

Topics: Acetophenones; Animals; Benzopyrans; Cell Membrane Permeability; Connexin 43; Enkephalin, Leucine-2-Alanine; Enzyme Inhibitors; Gap Junctions; Myocardial Ischemia; Phosphorylation; Protein Kinase C-epsilon; Rats; Rats, Sprague-Dawley; Receptors, Opioid, delta

Opioid peptides, which can induce mammalian hibernation, may provide protection against subcellular and molecular changes during hypothermic myocardial ischemia. This study examined the differential effects of the three known myocyte opioid receptors, Mu (micro), Delta (delta), and Kappa (kappa), in augmenting myocardial ischemic tolerance.. Control hearts (CH) were compared to hearts pretreated with either the micro-agonist, fentanyl, the delta-agonist, DADLE, or delta-antagonist, NTB, or the kappa-agonist, U50488H (U50), or kappa-antagonist, nor-BNI. The percent return of isovolemic developed pressure (LVDP), myocardial oxygen consumption (MVO(2)), and coronary flow (CF) following 2 h of global hypothermic cardioplegic ischemia were recorded in isolated Langendorff perfused hearts.. At 45 min of reperfusion, hearts pretreated with either DADLE or U50488H demonstrated significantly improved functional recovery versus controls (P < 0.05) and significantly depressed recovery with NTB or nor-BNI pretreatment (P < 0.05). Pretreatment with fentanyl was not significantly different than controls. Furthermore, DADLE, U50488H, or fentanyl resulted in increased MVO(2) versus controls (P < 0.05). There was no difference in CF between all groups.. This study demonstrates that the micro-receptor does not appear to confer a beneficial effect. However, selective delta- and kappa-agonists provide significant myocardial protection. Moreover, hearts pretreated with an opioid antagonist showed a marked decrement in both functional and metabolic integrity. These results taken together would imply a positive and negative constitutive role of delta- and kappa-opioids in the regulation of myocardial ischemic tolerance. This utilization of opioid receptor stimulation may have profound clinical applications.

Topics: 3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; Adaptation, Physiological; Animals; Cardiotonic Agents; Enkephalin, Leucine-2-Alanine; Fentanyl; Heart; In Vitro Techniques; Microscopy, Electron; Myocardial Ischemia; Myocardial Reperfusion; Myocardium; Opioid Peptides; Oxygen Consumption; Rabbits; Recovery of Function

The cardioprotective effects of delta-opioid receptor agonists is mediated-at least in part-via oxygen radicals. Mannitol that is used in cardiac surgery because of its osmotic properties exerts its beneficial effects on stunned myocardium via scavenging hydroxyl radicals. The effects of a delta-opioid receptor agonist (D-Ala2-D-Leu5-Enkephalin [DADLE]), the radical scavenger mannitol and their combination on postischemic dysfunction in rabbit hearts were investigated.. Isolated, blood-perfused rabbit hearts were subjected to a 20-min global, normothermic, no-flow ischemia that was followed by a 60-min reperfusion. Systolic and diastolic ventricular function as well as coronary blood flow (CBF) were assessed. The hearts were assigned to one of four groups: 1. placebo (n = 6); 2. DADLE (n = 8; 430 nM); 3. mannitol (n = 7; 8.6 mM); 4. DADLE + mannitol (n = 7).. Ischemic contracture in the DADLE and the mannitol group was significantly smaller compared with the placebo group. Contracture was smallest in the DADLE + mannitol group. The postischemic function in the placebo group was drastically reduced (p < 0.05), while it was best preserved in the DADLE + mannitol group. CBF and MVO(2) were changed similarly in all groups (n. s.). The external efficiency was significantly higher in the groups with DADLE and/or mannitol than in the placebo group. Both DADLE and mannitol exhibit cardioprotective properties. Combination of both substances exerts an additive, positive effect on the ischemic contracture. Noteworthy, the protective effects of DADLE during reperfusion were not antagonized by the oxygen radical scavenger mannitol. On the other hand, DADLE + mannitol did not augment the protective effects of the single substances during reperfusion, except for the isovolumic LVP(max).. Both substances improve the postischemic systolic and diastolic function and the relation between cardiac work and oxygen needed for this work. Thus, both substances offer promising properties in the clinic.

Topics: Analgesics, Opioid; Animals; Drug Combinations; Enkephalin, Leucine-2-Alanine; Free Radical Scavengers; Heart Rate; Male; Mannitol; Myocardial Contraction; Myocardial Ischemia; Myocardial Reperfusion Injury; Rabbits; Reactive Oxygen Species; Recovery of Function; Treatment Outcome

Perfusion of the isolated intact rat heart with Krebs-Henseleit solution containing agonists ((-)-TAN-67, DPDPE, and dalargin) or antagonists of delta-opioid receptors (naltrindole, TIPP[psi], and ICI 174,864) in a final concentration of 0.1 mg/liter was followed by a decrease in the heart rate, end-diastolic pressure, contraction rate, relaxation rate, and left ventricular developed pressure. Perfusion with a solution containing the delta-opioid receptor agonist DPDPE or delta-antagonists naltrindole, TIPP[psi], and ICI 174,864 before modeling of global ischemia increased the severity of reperfusion-induced contractile dysfunction in the myocardium. Our results suggest that delta-opioid receptor antagonists in vitro exhibit properties of partial delta-receptor agonists.

Topics: Animals; Enkephalin, D-Penicillamine (2,5)-; Enkephalin, Leucine; Enkephalin, Leucine-2-Alanine; Heart; In Vitro Techniques; Male; Myocardial Contraction; Myocardial Ischemia; Naltrexone; Oligopeptides; Perfusion; Quinolines; Rats; Rats, Wistar; Receptors, Opioid, delta

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

Opioids are involved in cardiac ischemic preconditioning. Important species differences in cellular signaling mechanisms, antiarrhythmic, and antistunning effects have been described. The role of the delta-opioid receptor activation in swine remains unknown. Forty minutes before a 45-min occlusion and 180-min reperfusion of the left anterior descending coronary artery, open-chest, pentobarbital-anesthetized swine received either 1) saline (controls); 2) [D-Ala(2),D-Leu(5)]enkephalin (DADLE); 3) [D-Pen(2,5)]enkephalin (DPDPE); 4) deltorphin-D, a novel delta(2)-opioid agonist; or 5) ischemic preconditioning (IP). Assessed were 1) infarct size to area at risk (IS, triphenyltetrazolium staining), 2) regional and global myocardial function (sonomicrometry, ventricular pressure catheters), and 3) arrhythmias (electrocardiogram analyses). It was found that DPDPE and deltorphin-D pretreatment reduced IS from 64.7 +/- 5 to 36.5 +/- 6% and 27.4 +/- 11% (P < 0.01), respectively, whereas DADLE had no effect (66.8 +/- 3%). Both IP and DADLE had a proarrhythmic effect (P < 0.01). However, no differences in global or regional myocardial function or arrhythmia scores were observed between groups. This suggests that delta-receptor-specific opioids provide cardioprotection in swine.

Topics: Animals; Arrhythmias, Cardiac; Cardiotonic Agents; Electrocardiography; Enkephalin, D-Penicillamine (2,5)-; Enkephalin, Leucine-2-Alanine; Hemodynamics; Ischemic Preconditioning, Myocardial; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion; Oligopeptides; Receptors, Opioid, delta; Species Specificity; Swine; Ventricular Pressure

Electrostimulation of the central gray matter in the sylvian aqueduct and nucleus raphe magnus produced an antiarrhythmic effect during acute myocardial ischemia. Stimulation and blockade of opiate receptors in the central amygdaloid nucleus and lateral hypothalamus with dalargin and naloxone induced the same effect. Destruction of the central gray matter in the sylvian aqueduct and nucleus raphe magnus decreased electrical stability of ischemic myocardium.

Topics: Amygdala; Animals; Anti-Arrhythmia Agents; Enkephalin, Leucine-2-Alanine; Heart; Hypothalamus; Male; Myocardial Contraction; Myocardial Ischemia; Naloxone; Narcotic Antagonists; Narcotics; Rats; Serotonin

Stimulation of the delta(1)-opioid receptor confers cardioprotection to the ischemic myocardium. We examined the role of protein kinase C (PKC) after delta-opioid receptor stimulation with TAN-67 or D-Ala(2)-D-Leu(5)-enkephalin (DADLE) in a rat model of myocardial infarction induced by a 30-min coronary artery occlusion and 2-h reperfusion. Infarct size (IS) was determined by tetrazolium staining and expressed as a percentage of the area at risk (IS/AAR). Control animals, subjected to ischemia and reperfusion, had an IS/AAR of 59.9 +/- 1.8. DADLE and TAN-67 administered before ischemia significantly reduced IS/AAR (36.9 +/- 3.9 and 36.7 +/- 4.7, respectively). The delta(1)-selective opioid antagonist 7-benzylidenenaltrexone (BNTX) abolished TAN-67-induced cardioprotection (54.4 +/- 1.3). Treatment with the PKC antagonist chelerythrine completely abolished DADLE- (61.8 +/- 3.2) and TAN-67-induced cardioprotection (55.4 +/- 4.0). Similarly, the PKC antagonist GF 109203X completely abolished TAN-67-induced cardioprotection (54.6 +/- 6.6). Immunofluorescent staining with antibodies directed against specific PKC isoforms was performed in myocardial biopsies obtained after 15 min of treatment with saline, chelerythrine, BNTX, or TAN-67 and chelerythrine or BNTX in the presence of TAN-67. TAN-67 induced the translocation of PKC-alpha to the sarcolemma, PKC-beta(1) to the nucleus, PKC-delta to the mitochondria, and PKC-epsilon to the intercalated disk and mitochondria. PKC translocation was abolished by chelerythrine and BNTX in TAN-67-treated rats. To more closely examine the role of these isoforms in cardioprotection, we utilized the PKC-delta selective antagonist rottlerin. Rottlerin abolished opioid-induced cardioprotection (48.9 +/- 4.8) and PKC-delta translocation without affecting the translocation of PKC-alpha, -beta(1), or -epsilon. These results suggest that PKC-delta is a key second messenger in the cardioprotective effects of delta(1)-opioid receptor stimulation in rats.

Topics: Acetophenones; Alkaloids; Analgesics; Animals; Benzophenanthridines; Benzopyrans; Benzylidene Compounds; Enkephalin, Leucine-2-Alanine; Enzyme Activation; Enzyme Inhibitors; Heart Rate; Indoles; Ischemic Preconditioning, Myocardial; Isoenzymes; Male; Maleimides; Myocardial Infarction; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Naltrexone; Narcotic Antagonists; Phenanthridines; Protein Kinase C; Protein Kinase C-delta; Quinolines; Rats; Rats, Wistar; Receptors, Opioid, delta

Topics: Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Cats; Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; Enkephalin, Leucine; Enkephalin, Leucine-2-Alanine; Enkephalins; Female; Heart; Lasers; Male; Myocardial Ischemia; Myocardium; Opioid Peptides; Receptors, Opioid; Sympathectomy

Cardiac transplant is hindered by donor shortage and preservation time. Extended extracorporeal preservation could increase the number and distribution of hearts for transplantation. Interestingly, mammalian hibernation biology closely parallels the altered cardiac cellular physiology noted with hypothermic organ storage. The present study undertook to test whether treatment with hibernation induction triggers could improve myocardial functional recovery following prolonged ischemic storage in a nonhibernating mammalian model. To study this hypothesis, isolated rabbit hearts had baseline functional and metabolic parameters recorded and then received either hypothermic storage only or standard cardioplegia, or cardioplegia containing 1 mg/kg D-Ala2-Leu5-enkaphalin (DADLE), which mimics natural hibernation, or preperfusion with DADLE, administered for 15 min at 2 mmol, 25 min prior to cardioplegic ischemia. Hearts were then subjected to 18 hr of global ischemic storage at 4 degrees C. Isovolumic developed pressure, coronary flows, and myocardial oxygen consumption were significantly improved with DADLE pretreatment vs. all groups after storage and reflow. Furthermore, DADLE hearts demonstrated better histological ultrastructure preservation following prolonged storage ischemia. This study demonstrates that hibernation protection with DADLE is beneficial for prolonged cardiac storage. The use of hibernation induction triggers is promising for organ preservation and deserve further mechanistic study.

Topics: Analysis of Variance; Animals; Cardioplegic Solutions; Enkephalin, Leucine-2-Alanine; Female; Heart; Heart Transplantation; Hibernation; Male; Myocardial Ischemia; Myocardial Reperfusion; Organ Preservation; Rabbits; Time Factors

Topics: Animals; Anti-Arrhythmia Agents; beta-Endorphin; Cats; Enkephalin, Leucine-2-Alanine; Female; Male; Motor Cortex; Myocardial Ischemia; Somatosensory Cortex; Tachycardia, Ventricular; Ventricular Fibrillation

Hypothermic cardioplegia provides adequate myocellular protection, yet stunning and dysfunction remain significant problems. Interestingly, the subcellular changes of hibernation parallel the altered biology of induced cardiac ischemia, but are well tolerated by hibernating mammalian myocardium. Hibernation induction trigger (HIT) from winter-hibernating animal serum induces hibernation in active animals. Hibernation induction trigger is opiate in nature and is similar to the delta 2 opioids.. To determine whether HIT could improve myocardial recovery following global ischemia, we gave 37 isolated rabbit hearts either standard cardioplegia or cardioplegia containing summer-active woodchuck, hibernating woodchuck, or black bear HIT serum or a delta 2 opioid, D-Ala2-Leu5-enkephalin, before 2 hours of global ischemia.. Hibernation induction trigger appeared not to have an active mechanism during ischemia, as all hearts had equal recovery. In contrast, when examining for a preischemia mechanism, 23 additional rabbits received 3 days pretreatment with summer-active woodchuck or HIT hibernating woodchuck or black bear serum, or were preperfused with D-Ala2-Leu5-enkephalin or D-pen2,5-enkephalin, a-delta 1 opioid, again before 2 hours of global ischemia. Postischemic ventricular function, coronary flows, myocardial oxygen consumption, and ultrastructural preservation were all significantly improved with HIT and D-Ala2-Leu5-enkephalin pretreatment.. "Natural" HIT protection is superior to standard cardioplegia alone and may have clinical application.

Topics: Analysis of Variance; Animals; Coronary Circulation; Disease Models, Animal; Enkephalin, D-Penicillamine (2,5)-; Enkephalin, Leucine-2-Alanine; Enkephalins; Female; Heart; Heart Arrest, Induced; Hibernation; Hypothermia, Induced; Male; Marmota; Myocardial Ischemia; Myocardial Stunning; Myocardium; Oxygen Consumption; Peptides; Premedication; Proteins; Rabbits; Receptors, Opioid, delta; Ursidae; Ventricular Function; Ventricular Function, Left; Ventricular Pressure

Topics: Animals; Anti-Arrhythmia Agents; Blood Pressure; Cats; Enkephalin, Leucine-2-Alanine; Female; Heart Rate; Male; Myocardial Ischemia; Sympathectomy; Sympatholytics; Ventricular Fibrillation

We studied antiarrhythmic action of D-Ala 2, Leu 5, Arg 6-enkephalin (dalargin) in experiments on male rats. Dalargin is reported to prevent heart rhythm disturbance and heart electrical stability decrease in experimental coronary occlusion, postinfarction, cardiosclerosis and emotional stress. Dalargin prevents acute myocardial ischaemia-induced increase of cAMP content in blood serum and cardiac muscle, as an indirect feature of its antiadrenergic activity. D-Ala 2, Leu 5, Arg 6-enkephalin leads to a decrease of cAMP content in myocardium and blood plasma, which presumably indicates a decrease of sympathetic tone. The data strongly suggest that cGMP content increase and somatostatin level decrease in cardiac muscle play a significant role in antiarrhythmic action of dalargin.

Topics: Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Chi-Square Distribution; Enkephalin, Leucine-2-Alanine; Male; Myocardial Ischemia; Rats

It has been established that preliminary administration of D-Ala2-Leu5-Arg6-enkephalin, D-Met2-Pro5-enkephalinamide, and D-phenylalanine to experimental animals prevents a stress-induced increase of the content of thromboxane in the blood plasma and myocardium and induces a rise of the level of prostacyclin, PGF2 and PGE in the heart and blood plasma. The authors hold that the changes in the level of prostanoids may mediate cardioprotective and anti-stressor rather than antiarrhythmic effects of enkephalins.

Topics: Animals; Anti-Arrhythmia Agents; Disease Models, Animal; Drug Evaluation, Preclinical; Enkephalin, Leucine-2-Alanine; Enkephalin, Methionine; Heart; Myocardial Ischemia; Myocardium; Prostaglandins; Stress, Physiological; Ventricular Fibrillation

In acute experiments on cats it has been shown that dalargin possess antiarrhythmic affect in myocardial ischemia. Antiarrythmic effect of dalagrig may be connected both with reflex and with direct action of dalargin on neurons structure, which

Topics: Animals; Anti-Arrhythmia Agents; Cats; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Enkephalin, Leucine-2-Alanine; Female; Heart; Heart Rate; Male; Myocardial Ischemia; Vagotomy; Ventricular Fibrillation

Adaptation of rats to cold and physical exercise prevented ventricular fibrillation (VF) caused by the occlusion of the left anterior coronary artery. In the heart of adapted rats with acute myocardial ischemia, myocardial enkephalins increased whereas the level of cAMP declined as compared to nonadapted animals. Injection of dalargin before the occlusion of the coronary artery in rats prevented both VF and a decrease of VF threshold. The peptide averted the rise of cAMP content in the heart during acute myocardial ischemia. The data obtained suggest that the rise of endogenous myocardial enkephalins may have an important role in antiarrhythmic action of adaptation. It is assumed that antiarrhythmic effect of enkephalins may be related to the restriction of sympathetic influence on the heart.

Topics: Acute Disease; Adaptation, Physiological; Animals; Cold Temperature; Enkephalin, Leucine-2-Alanine; Enkephalins; Exercise; Heart; Male; Myocardial Ischemia; Myocardium; Nucleotides, Cyclic; Rats; Rats, Wistar; Sympatholytics; Ventricular Fibrillation