Adaptation to chronic hypoxia represents a potential cardioprotective intervention reducing the extent of acute ischemia/reperfusion (I/R) injury, which is a major cause of death worldwide. The main objective of this study was to investigate the anti-apoptotic Akt/hexokinase 2 (HK2) pathway in hypoxic hearts subjected to I/R insult. Hearts isolated from male Wistar rats exposed either to continuous normobaric hypoxia (CNH; 10% O2) or to room air for 3 weeks were perfused according to Langendorff and subjected to 10 min of no-flow ischemia and 10 min of reperfusion. The hearts were collected either after ischemia or after reperfusion and used for protein analyses and quantitative fluorescence microscopy. The CNH resulted in increased levels of HK1 and HK2 proteins and the total HK activity after ischemia compared to corresponding normoxic group. Similarly, CNH hearts exhibited increased ischemic level of Akt protein phosphorylated on Ser473. The CNH also strengthened the interaction of HK2 with mitochondria and prevented downregulation of mitochondrial creatine kinase after reperfusion. The Bax/Bcl-2 ratio was significantly lower after I/R in CNH hearts than in normoxic ones, suggesting a lower probability of apoptosis. In conclusion, the Akt/HK2 pathway is likely to play a role in the development of a cardioprotective phenotype of CNH by preventing the detachment of HK2 from mitochondria at reperfusion period and decreases the Bax/Bcl-2 ratio during I/R insult, thereby lowering the probability of apoptosis activation in the mitochondrial compartment.

• Klíčová slova
• Heart, Hexokinase, Hypoxia, Ischemia/reperfusion, Mitochondria, Protein kinase B/Akt,
• MeSH
• hexokinasa metabolismus   MeSH
• krysa rodu Rattus MeSH
• myokard enzymologie   patologie   MeSH
• potkani Wistar MeSH
• protoonkogenní proteiny c-akt metabolismus   MeSH
• reperfuzní poškození myokardu enzymologie   patologie   MeSH
• srdeční mitochondrie enzymologie   patologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• hexokinasa MeSH
• protoonkogenní proteiny c-akt MeSH

Cytochrome oxidase activity from the retina can be enhanced or depressed by free radical-mediated reactions both in positive and negative aspect. The greatest effect was exerted by ischemia/reperfusion, which significantly increased the fluorescent products of lipid peroxidation (358 %, P < 0.01) and inhibited the enzyme activity (14%, P < 0.001). After hyperoxia the fluorescent products slightly increased (192%, P < 0.05) as well as the enzyme activity (133 %, P < 0.05). Hypoxia had no effect on any of these parameters. Specific changes in the composition of fluorophores after ischemia/reperfusion were revealed in the fluorescence spectra. The fact that increased lipid peroxidation after hyperoxia and after ischemia/reperfusion does not produce the same effect upon cytochrome oxidase activity might be explained by changes in the kinetic behavior of cytochrome oxidase. In the control enzyme preparation, two binding sites for cytochrome c were observed. One was of the low-affinity (Km = 60 microM) and the other of the high-affinity (Km = 1.12 microM). After in vitro-initiated lipid peroxidation, the low-affinity binding site was lost and the activity measured under "optimum" conditions at a single cytochrome concentration was higher than in the controls. This implies that oxidative damage to cytochrome oxidase in vivo can be site-specific and its extent should be estimated by performing detailed kinetic analysis as otherwise the results might be misleading.

• MeSH
• fluorescenční spektrometrie MeSH
• fosfáty farmakologie   MeSH
• hyperoxie metabolismus   MeSH
• hypoxie metabolismus   MeSH
• kinetika MeSH
• krysa rodu Rattus MeSH
• kyslík farmakologie   MeSH
• okluze retinální arterie metabolismus   MeSH
• peroxidace lipidů účinky léků   fyziologie   MeSH
• potkani Wistar MeSH
• pufry MeSH
• reperfuzní poškození metabolismus   MeSH
• respirační komplex IV metabolismus   MeSH
• retina enzymologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• fosfáty MeSH
• kyslík MeSH
• pufry MeSH
• respirační komplex IV MeSH

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.

• MeSH
• hypoxie patofyziologie   MeSH
• krysa rodu Rattus MeSH
• narkotika - antagonisté farmakologie   MeSH
• orgánové kultury - kultivační techniky MeSH
• potkani Wistar MeSH
• receptory opiátové delta antagonisté a inhibitory   fyziologie   MeSH
• receptory opiátové mu antagonisté a inhibitory   fyziologie   MeSH
• reperfuzní poškození myokardu patofyziologie   prevence a kontrola   MeSH
• srdeční mitochondrie účinky léků   fyziologie   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DOR2 protein, rat MeSH Prohlížeč
• narkotika - antagonisté MeSH
• receptory opiátové delta MeSH
• receptory opiátové mu MeSH

Epoxyeicosatrienoic acids (EETs) decrease cardiac ischemia-reperfusion injury; however, the mechanism of their protective effect remains elusive. Here, we investigated the cardioprotective action of a novel EET analog, EET-B, in reperfusion and the role of hypoxia-inducible factor (HIF)-1α in such action of EET-B. Adult male rats were subjected to 30 min of left coronary artery occlusion followed by 2 h of reperfusion. Administration of 14,15-EET (2.5 mg/kg) or EET-B (2.5 mg/kg) 5 min before reperfusion reduced infarct size expressed as a percentage of the area at risk from 64.3 ± 1.3% in control to 42.6 ± 1.9% and 46.0 ± 1.6%, respectively, and their coadministration did not provide any stronger effect. The 14,15-EET antagonist 14,15-epoxyeicosa-5( Z)-enoic acid (2.5 mg/kg) inhibited the infarct size-limiting effect of EET-B (62.5 ± 1.1%). Similarly, the HIF-1α inhibitors 2-methoxyestradiol (2.5 mg/kg) and acriflavine (2 mg/kg) completely abolished the cardioprotective effect of EET-B. In a separate set of experiments, the immunoreactivity of HIF-1α and its degrading enzyme prolyl hydroxylase domain protein 3 (PHD3) were analyzed in the ischemic areas and nonischemic septa. At the end of ischemia, the HIF-1α immunogenic signal markedly increased in the ischemic area compared with the septum (10.31 ± 0.78% vs. 0.34 ± 0.08%). After 20 min and 2 h of reperfusion, HIF-1α immunoreactivity decreased to 2.40 ± 0.48% and 1.85 ± 0.43%, respectively, in the controls. EET-B blunted the decrease of HIF-1α immunoreactivity (7.80 ± 0.69% and 6.44 ± 1.37%, respectively) and significantly reduced PHD3 immunogenic signal in ischemic tissue after reperfusion. In conclusion, EET-B provides an infarct size-limiting effect at reperfusion that is mediated by HIF-1α and downregulation of its degrading enzyme PHD3. NEW & NOTEWORTHY The present study shows that EET-B is an effective agonistic 14,15-epoxyeicosatrienoic acid analog, and its administration before reperfusion markedly reduced myocardial infarction in rats. Most importantly, we demonstrate that increased hypoxia-inducible factor-1α levels play a role in cardioprotection mediated by EET-B in reperfusion likely by mechanisms including downregulation of the hypoxia-inducible factor -1α-degrading enzyme prolyl hydroxylase domain protein 3.

• Klíčová slova
• epoxyeicosatrienoic acid, heart, hypoxia-inducible factor-1α, ischemia-reperfusion, prolyl hydroxylase 3,
• MeSH
• down regulace MeSH
• faktor 1 indukovatelný hypoxií - podjednotka alfa genetika   metabolismus   MeSH
• funkce levé komory srdeční účinky léků   MeSH
• infarkt myokardu enzymologie   patologie   patofyziologie   prevence a kontrola   MeSH
• kyselina 8,11,14-eikosatrienová analogy a deriváty   farmakologie   terapeutické užití   MeSH
• modely nemocí na zvířatech MeSH
• myokard enzymologie   patologie   MeSH
• potkani Sprague-Dawley MeSH
• prolyl-4-hydroxylasy HIF genetika   metabolismus   MeSH
• proteolýza MeSH
• remodelace komor účinky léků   MeSH
• reperfuzní poškození myokardu enzymologie   patologie   patofyziologie   prevence a kontrola   MeSH
• signální transdukce účinky léků   MeSH
• zvířata MeSH
• Check Tag
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• EET-B MeSH Prohlížeč
• Egln3 protein, rat MeSH Prohlížeč
• faktor 1 indukovatelný hypoxií - podjednotka alfa MeSH
• Hif1a protein, rat MeSH Prohlížeč
• kyselina 8,11,14-eikosatrienová MeSH
• prolyl-4-hydroxylasy HIF MeSH

Cardiac sensitivity to oxygen deprivation changes significantly during ontogenetic development. However, the mechanisms for the higher tolerance of the immature heart, possibilities of protection, and the potential impact of perinatal hypoxia on cardiac tolerance to oxygen deprivation in adults have not yet been satisfactorily clarified. The hypoxic tolerance of an isolated rat heart showed a triphasic pattern: significant decrease from postnatal day 1 to 7, followed by increase to the weaning period, and final decline to adulthood. We have observed significant ontogenetic changes in mitochondrial oxidative phosphorylation and mitochondrial membrane potential, as well as in the role of the mitochondrial permeability transition pores in myocardial injury. These results support the hypothesis that cardiac mitochondria are deeply involved in the regulation of cardiac tolerance to oxygen deprivation during ontogenetic development. Ischemic preconditioning failed to increase tolerance to oxygen deprivation in the highly tolerant hearts of newborn rats. Chronic hypoxic exposure during early development may cause in-utero or neonatal programming of several genes that can change the susceptibility of the adult heart to ischemia-reperfusion injury; this effect is sex dependent. These results would have important clinical implications, since cardiac sensitivity in adult patients may be significantly affected by perinatal hypoxia in a sex-dependent manner.

• Klíčová slova
• cardiac protection, cœur immature, hypoxic tolerance, immature heart, ontogeny, ontogénie, protection cardiaque, tolérance hypoxique,
• MeSH
• hypoxie buňky MeSH
• hypoxie embryologie   metabolismus   MeSH
• ischemická choroba srdeční embryologie   etiologie   metabolismus   MeSH
• kardiovaskulární komplikace v těhotenství metabolismus   MeSH
• lidé MeSH
• myokard metabolismus   MeSH
• reperfuzní poškození myokardu etiologie   metabolismus   MeSH
• srdce embryologie   růst a vývoj   MeSH
• srdeční mitochondrie metabolismus   MeSH
• těhotenství MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH

Epidemiological studies have demonstrated a relationship between the adverse influence of perinatal development and increased risk of ischemic heart disease in adults. From negative factors to which the fetus is subjected, the most important is hypoxia. The fetus may experience hypoxic stress under different conditions, including pregnancy at high altitude, pregnancy with anemia, placental insufficiency, and heart, lung, and kidney disease. One of the most common insults during the early stages of postnatal development is hypoxemia due to congenital cyanotic heart defects. Experimental studies have demonstrated a link between early hypoxia and increased risk of ischemia/reperfusion injury (I/R) in adults. Furthermore, it has been observed that late myocardial effects of chronic hypoxia, experienced in early life, may be sex-dependent. Unlike in males, perinatal hypoxia significantly increased cardiac tolerance to acute I/R injury in adult females, expressed as decreased infarct size and lower incidence of ischemic arrhythmias. It was suggested that early hypoxia may result in sex-dependent programming of specific genes in the offspring with the consequence of increased cardiac susceptibility to I/R injury in adult males. These results would have important clinical implications, since cardiac sensitivity to oxygen deprivation in adult patients may be significantly influenced by perinatal hypoxia in a sex-dependent manner.

• Klíčová slova
• cœur, différences entre les sexes, heart, hypoxie périnatale, ischemia/reperfusion injury, lésions d’ischémie/reperfusion, perinatal hypoxia, sex differences,
• MeSH
• dospělí MeSH
• hypoxie plodu komplikace   patofyziologie   MeSH
• ischemická choroba srdeční epidemiologie   etiologie   patofyziologie   MeSH
• kyslík metabolismus   MeSH
• lidé MeSH
• reperfuzní poškození myokardu epidemiologie   etiologie   patofyziologie   MeSH
• rizikové faktory MeSH
• sexuální faktory MeSH
• srdce embryologie   patofyziologie   MeSH
• těhotenství MeSH
• zpožděný efekt prenatální expozice epidemiologie   etiologie   patofyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mužské pohlaví MeSH
• těhotenství MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• kyslík MeSH

It has been documented that adaptation to hypoxia increases myocardial tolerance to ischemia-reperfusion (I/R) injury depending on the regimen of adaptation. Reactive oxygen species (ROS) formed during hypoxia play an important role in the induction of protective cardiac phenotype. On the other hand, the excess of ROS can contribute to tissue damage caused by I/R. Here we investigated the relationship between myocardial tolerance to I/R injury and transcription activity of major antioxidant genes, transcription factors, and oxidative stress in three different regimens of chronic hypoxia. Adult male Wistar rats were exposed to continuous normobaric hypoxia (FiO2 0.1) either continuously (CNH) or intermittently for 8 h/day (INH8) or 23 h/day (INH23) for 3 wk period. A control group was kept in room air. Myocardial infarct size was assessed in anesthetized open-chest animals subjected to 20 min coronary artery occlusion and 3 h reperfusion. Levels of mRNA transcripts and the ratio of reduced and oxidized glutathione (GSH/GSSG) were analyzed by real-time RT-PCR and by liquid chromatography, respectively. Whereas CNH as well as INH8 decreased infarct size, 1 h daily reoxygenation (INH23) abolished the cardioprotective effect and decreased GSH/GSSG ratio. The majority of mRNAs of antioxidant genes related to mitochondrial antioxidant defense (manganese superoxide dismutase, glutathione reductase, thioredoxin/thioredoxin reductase, and peroxiredoxin 2) were upregulated in both cardioprotective regimens (CNH, INH8). In contrast, INH23 increased only PRX5, which was not sufficient to induce the cardioprotective phenotype. Our results suggest that the increased mitochondrial antioxidant defense plays an important role in cardioprotection afforded by chronic hypoxia.

• Klíčová slova
• adaptation to hypoxia, antioxidant defense, cardioprotection, ischemia-reperfusion injury, oxidative stress,
• MeSH
• antioxidancia metabolismus   MeSH
• chromatografie kapalinová MeSH
• glutathionreduktasa genetika   MeSH
• hypoxie metabolismus   MeSH
• krysa rodu Rattus MeSH
• myokard metabolismus   MeSH
• oxidační stres fyziologie   MeSH
• peroxiredoxiny genetika   MeSH
• reperfuzní poškození myokardu metabolismus   MeSH
• superoxiddismutasa genetika   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antioxidancia MeSH
• glutathionreduktasa MeSH
• peroxiredoxiny MeSH
• superoxiddismutasa MeSH

(Pro)renin receptor (PRR) contributes to regulating many physiological and pathological processes; however, the role of PRR-mediated signaling pathways in myocardial ischemia/reperfusion injury (IRI) remains unclear. In this study, we used an in vitro model of hypoxia/reoxygenation (H/R) to mimic IRI and carried out PRR knockdown by siRNA and PRR overexpression using cDNA in H9c2 cells. Cell proliferation activity was examined by MTT and Cell Counting Kit-8 (CCK-8) assays. Apoptosis-related factors, autophagy markers and beta-catenin pathway activity were assessed by real-time PCR and western blotting. After 24 h of hypoxia followed by 2 h of reoxygenation, the expression levels of PRR, LC3B-I/II, Beclin1, cleaved caspase-3, cleaved caspase-9 and Bax were upregulated, suggesting that apoptosis and autophagy were increased in H9c2 cells. Contrary to the effects of PRR downregulation, the overexpression of PRR inhibited proliferation, induced apoptosis, increased the expression of pro-apoptotic factors and autophagy markers, and promoted activation of the beta-catenin pathway. Furthermore, all these effects were reversed by treatment with the beta-catenin antagonist DKK-1. Thus, we concluded that PRR activation can trigger H/R-induced apoptosis and autophagy in H9c2 cells through the beta-catenin signaling pathway, which may provide new therapeutic targets for the prevention and treatment of myocardial IRI.

• MeSH
• apoptóza fyziologie   MeSH
• autofagie fyziologie   MeSH
• beta-katenin metabolismus   MeSH
• buněčné linie MeSH
• hypoxie buňky fyziologie   MeSH
• kardiomyocyty metabolismus   patologie   MeSH
• krysa rodu Rattus MeSH
• kyslík metabolismus   MeSH
• receptor proreninu MeSH
• receptory buněčného povrchu metabolismus   MeSH
• reperfuzní poškození myokardu metabolismus   patologie   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• beta-katenin MeSH
• Ctnnb1 protein, rat MeSH Prohlížeč
• kyslík MeSH
• receptor proreninu MeSH
• receptory buněčného povrchu MeSH

• MeSH
• hypoxie buňky MeSH
• koronární nemoc metabolismus   MeSH
• kyslík metabolismus   MeSH
• lidé MeSH
• myokard metabolismus   MeSH
• reperfuze myokardu * MeSH
• vápník metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kyslík MeSH
• vápník MeSH

The present study was designed to investigate the ameliorative effect of cyclosporine A (CsA) pretreatment on an anoxia/reoxygenation injury model by using immobilized perfused hepatocytes. Rats received an i.p. injection of two successive doses of CsA (5 mg/kg/day). Twenty-four hours later hepatocytes were isolated from CsA-treated and control rats. After hepatocyte isolation, immobilization, perfusion, induction of anoxia/reoxygenation, the structural and functional integrity of the hepatocytes was followed in a perfusion medium by measuring the leakage of lactate dehydrogenase (LD) and the time course of urea biosynthesis. CsA pretreatment reduced the initial rate of urea synthesis during normoxia but reduced the drop in the relative percentage rate of urea synthesis during the period of anoxia. LD leakage was increased threefold by anoxia and sevenfold by reoxygenation in cells of untreated animals. After CsA pretreatment in vivo, hepatocytes showed no increase in LD leakage into the medium. These findings demonstrate that the perfused immobilized hepatocytes can be used as a cellular model to assess the effects of liver insults such as anoxia/reoxygenation injury and that CsA modulates the injury. The mechanisms of CsA beneficial effects at the experimental level remain to be elucidated.

• MeSH
• buněčná membrána metabolismus   MeSH
• cyklosporin farmakologie   MeSH
• hypoxie buňky MeSH
• imobilizované buňky MeSH
• imunosupresiva farmakologie   MeSH
• játra cytologie   účinky léků   metabolismus   MeSH
• krysa rodu Rattus MeSH
• kultivované buňky MeSH
• L-laktátdehydrogenasa metabolismus   MeSH
• močovina metabolismus   MeSH
• perfuze MeSH
• potkani Wistar MeSH
• reperfuzní poškození farmakoterapie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• cyklosporin MeSH
• imunosupresiva MeSH
• L-laktátdehydrogenasa MeSH
• močovina MeSH