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The role of Akt / protein kinase B in healthy and hypertrophied heart
Heleš, Mário ; Žurmanová, Jitka (advisor) ; Hrdlička, Jaroslav (referee)
Protein kinase B, or Akt kinase is expressed in almost all tissues. Two main isoforms in heart are Akt1 and Akt2, which are responsible for regulation of metabolism, growth and survival of cardiomyocytes. Akt kinase is among other pathways stimulated by insulin receptor and mechanoreceptor cascades and its main targets are mTORC1, AMPK and GSK- 3β. Akt kinase is activated in presence of chronic hemodynamic overload of heart. In dependence of intensity and duration of overload, Akt participate in triggering of either adaptive, fully reversible hypertrophy or detrimental irreversible form of hypertrophy, which causes impairment of pumping function of heart and can lead to heart failure. Many more factors with complex interactions participate in cardiac hypertrophy beside Akt kinase. Key words: heart, hypertrophy, Akt/protein kinase B, cardiac remodeling, insulin- like growth factor
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Gene expression of enzymes involved in the regulation of apoptosis in rat moycardium - effect of chronic and acute hypoxia
Blahová, Tereza ; Žurmanová, Jitka (advisor) ; Kalous, Martin (referee)
Adaptation to chronic hypoxia provides myocardial protection against ischemia - reperfusion injury (IR). Cardioprotective effect of adaptation depends on the degree and duration of hypoxic exposure and daily regime of adaptation. Certain protective regimes of adaptations to hypoxia have been reported to activate proapoptotic signaling pathways and bioactive sphingolipids were recently shown to play important role in the regulation of apoptosis in the heart. We aimed to determine the mRNA level of selected genes related to apoptotic pathways and to sphingolipid metabolism in two models of hypoxic adaptation, continous normobaric hypoxia (CNH 10% O2) with different exposures (4h, 48h, 120h, 21days) and intermitent hypobaric hypoxia (IHH 7000 m, 8h/day). Both ventricles, LV and RV, were analysed after adaptation to CNH and only LV was analysed after IHH adaptation. Our results show that both types of adaptation increased mRNA of proapoptotic genes, CNH mainly in RV and IHH in LV. Furthermore, increased expressions of proapoptotic genes were accompanied by the increase of expression of enzymes producing predominantly protective kinds of sphingolipids. The exact role of apoptosis and sphingolipid signaling molecules in endogenous myocardial protection requires further research. Key words: Apoptosis,...
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Effect of chronic hypoxia on antioxidative capacity of rat myocardium.
Závišková, Kristýna ; Nováková, Olga (advisor) ; Žurmanová, Jitka (referee)
Adaptation to chronic hypoxia activates endogenous signaling cascades, which lead to cardiac protection against acute ischemia/reperfusion (I/R) injury. The molecular mechanism of this phenomenon has not been fully clarified yet. However, it was proved that reactive oxygen species (ROS) take part in cardioprotective signaling pathway inducted by chronic hypoxia. The high level of ROS must be precisely regulated by antioxidative system of a cell. The aim of diploma thesis was to examine the effect of intermittent hypobaric hypoxia (IHH, 7 000 m) on relative amount of antioxidative enzymes (peroxiredoxin 6 - PRX6, thioredoxin 1 and 2 - TRX1 and TRX2, thioredoxin reductase 1 - TRXR1) and also enzymes of iron metabolism (heme oxygenase 1 and 2 - HO1 and HO2, aconitase 1 and 2 - ACO1 and ACO2), which participate in regulation of cell redox state. Moreover, we studied the effect of adaptation to IHH and an antioxidant tempol on relative amount of calcium-independent phospholipase A2 (iPLA2). iPLA2 can remove peroxidized fatty acids from membrane phospholipids. On the other hand, iPLA2 can damage cell in I/R conditions. All enzymes were studied in homogenates from normoxic and IHH adapted rat left ventricular myocardium by Western blot. Adaptation to IHH caused a decrease of PRX6 and on the opposite an increase of...
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Pharmacological and metabolic influence on liver mitochondrial functions
Sobotka, Ondřej ; Červinková, Zuzana (advisor) ; Kuncová, Jitka (referee) ; Žurmanová, Jitka (referee)
Liver mitochondria play a crucial role in intermediary metabolism and main metabolic pathways. We evaluated the pharmacological effect on liver mitochondria in vitro using two novel anticancer drugs: 3-bromopyruvate and α-tocopheryl succinate. Metabolic influence on liver mitochondria was performed in vivo by high fat and high cholesterol diet. Toxicity of both drugs was evaluated in cell cultures of hepatocytes isolated from rat and mouse liver. The effect of anticancer drugs on liver mitochondrial functions in vitro was studied on suspensions of isolated liver mitochondria, tissue homogenate and permeabilized hepatocytes. Mitochondrial respiration was measured using high-resolution respirometry. 3-bromopyruvate caused morphological and functional damage of primary rat and mouse hepatocytes in cell cultures; this toxic effect was accompanied by an increase of reactive oxygen species production and mitochondrial dysfunction. 3-bromopyruvate decreased the oxygen consumption of mitochondria energized by substrates for complex I and complex II. α-Tocopheryl succinate caused a decrease of succinate-dependent respiration in all experimental models both in coupled and in uncoupled states. The most pronounced effect of α-tocopheryl succinate was apparent in isolated mitochondria and the least pronounced...
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Cardioprotective effect of adaptations to hypoxia and cold: Connexin 43 and hexokinase 2
Kohútová, Jana ; Žurmanová, Jitka (advisor) ; Radošinská, Jana (referee) ; Barančík, Miroslav (referee)
Ventricular arrhythmias are the main cause of death worldwide. An increased incidence of arrhythmias in the heart of mammals is accompanied by a remodeling of the cellular distribution gap between the channels of mainly connexin 43 (Cx43). Recently has been demonstrated significant effect of mitochondria and their association with arrhythmogenesis. Various pathological conditions alter the expression and / or distribution of Cx43, depending on the phosphorylation status. but also on altering the association of hexokinase with mitochondria, which reduces the likelihood of apoptosis activation. Adaptation to intermittent hypobaric hypoxia potentiates endogenous pathways reducing the incidence of ventricular arteries, whereas continuous normobaric hypoxia does not have this effect. Another studied model is cold acclimatization, which has been known for several decades by known effects on human health. However, the heart study of these models in relation to Cx43 is missing. Our goal was to determine the expression of Cx43, phosphorylated Cx43 (p-Cx43) and hexokinase (HK1, HK2) and their distribution in cardiomyocytes. In addition, the expression of Cx43 upstream kinases, protein kinase A, protein kinase G, casein kinase 1 in normoxic and hypoxic left ventricles of rats, along with Cx43 distribution...
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The role of adipose tissue in the whole-body energy metabolism in mice with different genetic background
Funda, Jiří ; Janovská, Petra (advisor) ; Pecina, Petr (referee) ; Žurmanová, Jitka (referee)
Adipose tissue greatly contributes to the maintenance of the whole-body energy homeostasis. White adipose tissue (WAT) is the most important storage of metabolic energy in the body, while brown adipose tissue (BAT) enables the body to survive in cold environment by transforming metabolic energy to heat. Both WAT and BAT have a critical role in the control of systemic levels of fatty acids, which is necessary for the maintenance of the energy homeostasis and for the prevention of lipotoxic damage of non-adipose tissues. Abundant lipid accumulation can lead to the development of obesity, which is often accompanied by metabolic disorders such as type 2 diabetes and by the impairment of adipose tissue metabolic functions. Healthy adipose tissue prevents from the development of metabolic disorders associated with obesity by buffering the excess of nutrients. The key processes for efficient buffering of fatty acids are futile triacylglycerols/fatty acid cycling (TAG/FA cycling) and fatty acid oxidation. These processes occur in both WAT and BAT and their rates are largely affected by a set of transcriptional regulators, especially peroxisome proliferator-activated receptors (PPARs) and their coactivators. Bioactive molecules such as hormones, polyunsaturated fatty acids (PUFA) or pharmaceutics such as...
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The role of beta1 adrenergic receptors in heart of cold acclimated rat
Liptáková, Andrea ; Žurmanová, Jitka (advisor) ; Nováková, Olga (referee)
During cold acclimation the heat production is shifted from shivering to non-shivering thermogenesis, which is mediated by adrenergic signaling. It has also been observed, that cold acclimation may increase the organismal resistence to pathological stimuli and may affect functional parameters of cardiovascular system. However, acute exposure to sever cold is often associated with detrimental effects on the body. We have recently shown that chronic exposure to cold increases the heart's resistance to ischemia-reperfusion injury without negative side effects when mild temperatures are used, however the mechanism of protection is not yet known. The aim of this work was to determine whether: i) if the sensitivity of the heart to ischemia changes already after the first day of cold exposure and does not show any negative effects, ii) if β1-adrenergic signaling plays a role in chronic regimen of cold-induced cardioprotection. The results of this work showed that i) one day of exposure to mild cold did not change the sensitivity of the heart to ischemia and ii) metoprolol treatment reduced the infarct size in the control group, but did not affect the heart of cold-adapted rats. Key words : Heart, rat, beta 1 adrenergic receptors, cold acclimation
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The role of lactate shuttle in ischemic-reperfusion injury of rat heart adapted to chronic hypoxia
Kolář, David ; Žurmanová, Jitka (advisor) ; Nováková, Olga (referee)
Adaptation to hypoxia is a well-known phenomenon increasing myocardial resistance to ischemia-reperfusion (I/R) injury as an appropriate physical exercise which improves the contractile function of the heart. Lactate is a major energy substrate for the heart muscle during physical activity and hypoxia. The metabolism of lactate was and still is associated with muscle fatigue, but in the last decades it has been considered its significant modulating function of metabolism during exercise at cellular level and whole organism level. It has been shown that its effects might be similar to the effects of hypoxia and its oxidized form, pyruvate, has the cardioprotective effects. The aim of this study was to compare the expression of LDHA and LDHB isoforms between left and right ventricle in the cardioprotective scheme of adaptation to hypoxia. Another objective/goal was to determine the left ventricular response to I/R insult in the perfused heart model adapted to hypoxia compared with the normoxic controls on/at the expression level of both LDH isoforms. Our results showed differences in the LDHA expression in the left and right ventricle and an increased response of the left ventricle to I/R insult in rats adapted to hypoxia which is reflected at the expression level of both isoforms. Key words: heart,...
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Calcium homeostasis and modulation of nociceptive synaptic transmission
Sojka, David ; Paleček, Jiří (advisor) ; Žurmanová, Jitka (referee) ; Krůšek, Jan (referee)
2 SUMMARY OF THE THESIS This study was designed to improve our knowledge regarding mechanisms of nociceptive signaling at spinal cord level. One of the forms of spinal cord synaptic transmission modulation is central sensitization, a manifestation of synaptic plasticity at spinal cord level, which was found to be present at many chronic pain syndromes. This study deals mainly with a development of calcium imaging technique with a final goal to study mechanisms of central sensitization in vitro on population of dorsal horn neurons. We have analyzed synaptically evoked intracellular Ca changes as a result of dorsal root stimulation in a superficial dorsal horn area in spinal cord slices and found two types of Ca responses: one synchronized with electrical stimulation and a second one, delayed response due to Ca release from internal stores. The delayed Ca release was not previously shown to be present in these neurons and it was not dependent on activation of ionotropic glutamatergic receptors, suggesting involvement of metabotropic receptor pathway. The presence of this delayed type of Ca response could have a significant role in the induction of some types of chronic pain syndromes since intracellular calcium increase is thought to be a key trigger point in spinal cord neurons sensitization. An important...
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