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Chronic continuous normobaric hypoxia (CNH) increases cardiac tolerance to ischemia/reperfusion injury in vivo and this effect is mediated via µ and δ2 opioid receptors (ORs) activation. CNH has also been shown to be cardioprotective in isolated rat heart. In this study, we hypothesize that this cardioprotective effect of CNH is mediated by activation of µ and δ2 ORs and preservation of mitochondrial function. Hearts from rats adapted to CNH (12% oxygen) for 3 weeks were extracted, perfused in the Langendorff mode and subjected to 45 min of global ischemia and 30 min of reperfusion. Intervention groups were pretreated for 10 min with antagonists for different OR types: naloxone (300 nmol/l), the selective d OR antagonist TIPP(ψ) (30 nmol/l), the selective d1 OR antagonist BNTX (1 nmol/l), the selective δ2 OR antagonist naltriben (1 nmol/l), the selective peptide µ OR antagonist CTAP (100 nmol/l) and the selective δ OR antagonist nor-binaltorphimine (3 nmol/l). Creatine kinase activity in coronary effluent and cardiac contractile function were monitored to assess cardiac injury and functional impairment. Additionally, cardiac tissue was collected to measure ATP and to isolate mitochondria to measure respiration rate and calcium retention capacity. Adaptation to CNH decreased myocardial creatine kinase release during reperfusion and improved the postischemic recovery of contractile function. Additionally, CNH improved mitochondrial state 3 and uncoupled respiration rates, ADP/O, mitochondrial transmembrane potential and calcium retention capacity and myocardial ATP level during reperfusion compared to the normoxic group. These protective effects were completely abolished by naloxone, TIPP(ψ), naltriben, CTAP but not BNTX or nor-binaltorphimine. These results suggest that cardioprotection associated with adaptation to CNH is mediated by µ and δ2 opioid receptors activation and preservation of mitochondrial function. [ABSTRACT FROM AUTHOR]

The objectives of this study were to investigate the role of endogenous opioids in the mediation of stress-induced cardiomyopathy (SIC), and to evaluate which opioid receptors regulate heart resistance to immobilization stress. Wistar rats were subjected to 24 h immobilization stress. Stress-induced heart injury was assessed by 99mTc-pyrophosphate accumulation in the heart. The opioid receptor (OR) antagonists (naltrexone, NxMB - naltrexone methyl bromide, MR 2266, ICI 174.864) and agonists (DALDA, DAMGO, DSLET, U-50,488) were administered intraperitoneally prior to immobilization and 12 h after the start of stress. In addition, the selective μ OR agonists PL017 and DAMGO were administered intracerebroventricularly prior to stress. Finally pretreatment with guanethidine was used. Naltrexone did not alter the cardiac 99mTc-PP accumulation in stressed rats. NxMB aggravated stress-induced cardiomyopathy (P=0.005) (SIC). The selective μ OR agonist DALDA, which does not cross the blood-brain barrier, completely prevented (P=0.006) SIC. The μ OR agonist DAMGO exhibited weaker effect than DALDA. The selective δ ligand (DSLET) and κ OR ligand (U-50,488) did not alter stress-induced 99mTc-pyrophosphate accumulation in the heart. Intracerebroventricular administration of the μ OR agonists aggravated SIC. Pretreatment with guanethidine abolished this effect (P=0.01). Guanethidine alone exhibited cardioprotective properties. A stimulation of central μ OR promotes an appearance of SIC. In contrast, stimulation of peripheral μ OR contributes to an increase in cardiac tolerance to stress. [ABSTRACT FROM AUTHOR]

We studied the role of the δ, μ, and к opioid receptor (OR) subtypes in the cardioprotective effect of chronic continuous normobaric hypoxia (CNH) in the model of acuteanoxia/ reoxygenation of isolated cardiomyocytes. Adaptation of rats to CNH was performed by their exposure to atmosphere containing 12 % of O2 for 21 days. Anoxia/reoxygenation of cardiomyocytes isolated from normoxic control rats caused the death of 51 % of cells and lactate dehydrogenase (LDH) release. Adaptation of rats to CNH resulted in the anoxia/reoxygenation-induced cardiomyocyte death of only 38 %, and reduced the LDH release. Pre-incubation of the cells with either the non-selective OR blocker naloxone (300 nM/l), the δ OR antagonist TIPP(Ψ (30 nM/l), the selective δ2 OR antagonist naltriben (1 nM/l) or the μ OR antagonist CTAP (100 nM/l) for 25 minutes before anoxia abolished the reduction of cell death and LDH release afforded by CNH. The antagonist of δ1 OR BNTX (1 nM/l) or the κ OR antagonist nor-binaltorphimine (3 nM/l) did not influence the cytoprotective effects of CNH. Taken together, the cytoprotective effect of CNH is associated with the activation of the δ2 and μ OR localized on cardiomyocytes. [ABSTRACT FROM AUTHOR]

Chronic continuous normobaric hypoxia (CNH) increases cardiac tolerance to ischemia/reperfusion injury in vivo and this effect is mediated via µ and delta2 opioid receptors (ORs) activation. CNH has also been shown to be cardioprotective in isolated rat heart. In this study, we hypothesize that this cardioprotective effect of CNH is mediated by activation of µ and delta2 ORs and preservation of mitochondrial function. Hearts from rats adapted to CNH (12 % oxygen) for 3 weeks were extracted, perfused in the Langendorff mode and subjected to 45 min of global ischemia and 30 min of reperfusion. Intervention groups were pretreated for 10 min with antagonists for different OR types: naloxone (300 nmol/l), the selective delta OR antagonist TIPP(psi) (30 nmol/l), the selective delta1 OR antagonist BNTX (1 nmol/l), the selective delta2 OR antagonist naltriben (1 nmol/l), the selective peptide µ OR antagonist CTAP (100 nmol/l) and the selective delta OR antagonist nor-binaltorphimine (3 nmol/l). Creatine kinase activity in coronary effluent and cardiac contractile function were monitored to assess cardiac injury and functional impairment. Additionally, cardiac tissue was collected to measure ATP and to isolate mitochondria to measure respiration rate and calcium retention capacity. Adaptation to CNH decreased myocardial creatine kinase release during reperfusion and improved the postischemic recovery of contractile function. Additionally, CNH improved mitochondrial state 3 and uncoupled respiration rates, ADP/O, mitochondrial transmembrane potential and calcium retention capacity and myocardial ATP level during reperfusion compared to the normoxic group. These protective effects were completely abolished by naloxone, TIPP(psi), naltriben, CTAP but not BNTX or nor-binaltorphimine. These results suggest that cardioprotection associated with adaptation to CNH is mediated by µ and delta2 opioid receptors activation and preservation of mitochondrial function.

Purpose: To study capabilities of perfusion-metabolic myocardial scintigraphy for prediction of the left ventricular (LV) reverse remodeling after comprehensive surgical treatment of ischemic cardiomyopathy (ICMP)., Methods: The study included ICMP patients aged 56±7 years (n=32) who underwent surgical correction of LV dysfunction (myocardial revascularization, LV reconstruction, and mitral valve restoration). Inclusion criteria were significant coronary artery disease; myocardial infarction; New York Heart Association (NYHA) class III-IV heart failure; LV ejection fraction (EF) ≤45%; LV end-systolic index (ESI) >60 mL/m2; and LV akinesia or dyskinesia according to echocardiography. Before surgery all patients were subjected to scintigraphy with 99mTc-MIBI (to assess perfusion) and with 123I-BMIPP (to assess myocardial metabolism). Scintigraphy results were expressed as median and lower; upper quartile (Me [lQ; hQ]). The clinical status and ventricular volume indicators were evaluated before surgery, in the early post-operative period (up to 4 weeks), and in the late post-operative period (12 months)., Results: At 12 months after intervention patients were divided into two groups: group 1 comprised patients (n=18) with beneficial outcome of the operation that stopped LV remodeling (ESI decreased, remained unchanged, or increased by.

Background: Twenty two patients with congestive cardiac failure treated surgically by dynamic cardiomyoplasty (CMP) with m. latissimus dorsi were examined. Myocardial perfusion was assessed with (199)TlCl scintigraphy combined with dipyridamole stress-test. In order to obtain direct evidence of myocardial perfusion from muscular flap we also injected a bolus of (99m)Tc into a. thoracodorsalis, with simultaneous blood sampling from coronary sinus. Haemodynamic parameters were assessed using radionuclide angiography., Methods: In a year of follow-up all the patients were assigned to one of two groups: eleven patients demonstrated improvement in clinical status (first group) and in another group comprising eleven persons no positive effect or deterioration were obvious (second group). The patients of the first group before operation revealed two times less persistent defect size than patients of the second group. Analysis of integral index of persistent defect revealed more expressive differences between groups. Before the surgical treatment the patients with improvement in clinical status after cardiomyoplasty demonstrated greater size of reversible defect in comparison with patients of the second group. In the second group coronary fraction of thallium accumulation was 1.4 times higher in comparison to the first group, as the result of myocardial hypertrophy in patients with bad prognosis. There were no significant differences between the two groups in Il/m level before cardiomyoplasty. Before the surgical treatment the patients with improvement in clinical status after cardiomyoplasty demonstrated greater ejection fraction in comparison with patients of the second group., Results: Cardiomyoplasty led to a decrease in the mean size of reversible defects due to indirect revascularisation. This hypothesis was testified to by the fact that in patients after cardiomyoplasty nuclide appeared in coronary sinus at 10-12th seconds after injection into artery thoracodorsalis through anastomoses between the latissimus dorsi muscle and the myocardium. The time of appearance of the second wave of rise gamma-counting in blood samples from coronary sinus reflects the repeated entry of radiopharmaceutical in myocardium after recirculation.

1. The kappa 1 and kappa 2 opioid receptor agonists U-62066 (8 mg/kg, i.p.) and (-)-bremazocine (0.7 mg/kg, i.v.), respectively, both exhibit anti-arrhythmic properties against adrenaline-induced dysrhythmias in rats. 2. In contrast, (+)-bremazocine has no effect on adrenaline-induced dysrhythmias. 3. The kappa 1 opioid receptor agonists U-50488 (110 nmol) and [D-Ala2]-dynorphin A (20 nmol) and the kappa 2 opioid receptor agonist (-)-bremazocine (30 nmol) exhibit pro-arrhythmic properties following intracerebroventricular administration. 4. Prior administration of the kappa opioid receptor antagonist nor-binaltorphimine doses i.c.v. (14 nmol), i.p. (10 mg/kg), completely abolishes the pro-arrhythmic (BNI, i.c.v., 14 nmol) as well as anti-arrhythmic (BNI, 10 mg/kg, i.p.) effects of the kappa opioid receptor agonists. 5. Neither hexamethonium (10 mg/kg, i.v.) nor atropine (1 mg/kg, i.v.) have any effect on the anti-arrhythmic actions of the kappa 1 opioid receptor agonist U-62066 following systemic administration. 6. It is suggested that the anti-arrhythmic effects of U-62066 and (-)-bremazocine are associated with the activation of peripheral kappa opioid receptors and do not depend on the activation of kappa opioid receptors in the autonomic nervous system.

The effect of kappa receptors agonists and antagonists was studied in the model of epinephrine induced arrhythmias. Kappa receptor agonists U-50,488 and [D-Ala2]-Dynorphin A (1-13) administered I.C.V. potentiate the arrhythmogenic effect of epinephrine. The effect of U-50,488 was completely blocked by kappa receptor antagonist, nor-binaltorphine. Administration of N-cholinergic receptor inhibitor, hexamethonium, prevented pro-arrhythmic effects of U-50,488 and [D-Ala2]-Dynorphin A (1-13). The data support the hypothesis that central kappa opioid receptors play an important role in the arrhythmogenesis.

The efficacy of a new radionuclide, thallium-199 for myocardial scintigraphy was compared with conventional thallium-201 imaging. Owing to the short half-life of thallium-199 (7.4 hours), when the injected dose of thallium-199 was increased to 200 MBq, the total dose reaching the critical organs was 3.6-15.5 times lower than with conventional nuclide, thallium-201. Studies were performed in a total of 177 patients. The patients were divided into two groups(a) 17 patients with acute myocardial infarction and (b) 160 patients undergoing coronary angiography: 55 patients with no significant coronary artery disease and 105 patients with coronary disease. The sensitivity of the test was 92% with a specificity of 82% and overall predictive accuracy of 84%. Myocardial images obtained with low and high energy collimators have similar predictive accuracy. Perfusion defects were detected more frequently with increasing severity of angina. Myocardial infarction was characterized by persistent defects and myocardial ischaemia by redistribution of thallium. Thallium-199 myocardial scintigraphy performed at rest can be used for the diagnosis of acute myocardial infarction and for the determination of infarct site and extent. Thallium-199 is a new myocardial imaging agent, with a predictive accuracy for the diagnosis of coronary artery disease similar to thallium-201, but a significantly reduced total body dose permits repeat studies with a reduced radiation dose for the patient.