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Tato práce je věnována výpočtu a analýze parametrů srdeční funkce, které je možné stanovit z obrazových dat pořízených magnetickou rezonancí. Pro výpočet byly použity ručně anotované snímky pořízené v krátké srdeční ose. Objemové parametry byly dopočítány přímo z obrazových dat sečtením voxelů náležejícím k příslušným strukturám srdce a následným vynásobením objemem voxelu. Funkční parametry byly následně dopočítány dle oficiálních definic z objemových parametrů. Dále byla stanovena tloušťka stěny myokardu levé komory pomocí modifikované radiální metody a kontraktilita myokardu pomocí segmentální deformační analýzy. Výsledné hodnoty byly vyneseny do tabulky a zobrazeny box–ploty. Dále byla provedena korelační analýza a následná zkouška klasifikačního stromu na vypočtených datech., The thesis is focused on calculation and analysis of heart function parameters which could be calculated from image data obtained by magnetic resonance. Manually annotated image data in short axis of heart were used for calculation. Volumetric parameters were calculated directly from image data by counting voxels which were parts of specific heart structure and then multiplied by voxel volume. Modified radial method was used to compute functional parameters whereas myocardial contractility was calculated by using segmental strain analysis. Obtained results were given into table and visualised in box– plots. Correlation analysis of parameters was also performed and decision tree classifier was used to test discrimination capacity of estimated parameters.

© 2016, Springer Science+Business Media New York.Stimulation of β-adrenoreceptors with low (10–8 and 10–7 M) or high (10–6 M) doses of isoproterenol in hypokinetic rats treated with L-NAME (a non-selective blocker of NO synthases) decreased or increased myocardial contractility, respectively. In control rats, all examined doses of isoproterenol used under blockade of NO synthases inhibited myocardial contractility.

Hydrogen sulfide (H2S) is an endogenously synthesized gaseous molecule which, along with nitric oxide and carbon monoxide, induces a number of effects in cardiovascular system under normal and pathological conditions. In the present work, the effects and underlying mechanisms of the H2S donor sodium hydrosulfide (NaHS) on the isometric force of frog myocardium contraction have been studied. NaHS at the concentration of 100 μM induced negative inotropic effect and reduced the maximum velocity of the contraction and relaxation of the isolated ventricle strips. The substrate of H2S synthesis, L-cysteine (200 μM and 1 mM), induced the same effect, while the inhibitors of cystathionin-γ-lyase, the H2S-producing enzyme in heart, β-cyanoalanine (500 μM) and propargylglycine (500 μM), increased the amplitude of contraction. Inhibition of cystathionin-γ-lyase by β-cyanoalanine prevented the negative inotropic effect of L-cysteine. After the inhibition of adenylate cyclase by MDL-12,330A (3 μM) or phosphodiesterases by IBMX (200 μM), the effect of NaHS was less than that in the control. In the presence of membrane-penetrating analogous of cAMP, 8Br-cAMP (100 μM) and pCPT-cAMP (100 μM), the negative inotropic effect of NaHS was completely retained. The effect of NaHS significantly decreased after preliminary application of the NO donor, SNAP (10 μM), and did not change after the inhibition of NO synthases by L-NAME (100 μM). The results suggest the possibility of endogenous synthesis of H2S in frog myocardium and regulation of its contractility by the activation of phosphodiesterases hydrolyzing cAMP, which leads to a decrease in the activation of cAMP-dependent protein kinases and phosphorylation of voltage-dependent L-type Ca channels. As a result, the reduction of calcium entry into cardiomyocytes decreases the contractility of frog myocardium. © 2013 Pleiades Publishing, Ltd.

Experiments with selective agonists and antagonists of purinoceptors allowed us to evaluate the subtype of P2X receptors. We showed that the myocardium of 14-100-day-old rats contains functionally active P2X 1 receptors. These receptors are involved in the realization of the positive inotropic effect of the atria and ventricles. Selective P2X 1 receptor agonist β,γ-methylene-ATP induced a dose-dependent increase in the strength of atrial and ventricular contractions. P2X 1 receptor antagonist TNP-ATP abolished the effect of the agonist in rats of all age groups. © Springer Science+Business Media, Inc. 2008.

© 2016, Springer Science+Business Media New York.Stimulation of β-adrenoreceptors with low (10–8 and 10–7 M) or high (10–6 M) doses of isoproterenol in hypokinetic rats treated with L-NAME (a non-selective blocker of NO synthases) decreased or increased myocardial contractility, respectively. In control rats, all examined doses of isoproterenol used under blockade of NO synthases inhibited myocardial contractility.

Hydrogen sulfide (H2S) is an endogenously synthesized gaseous molecule which, along with nitric oxide and carbon monoxide, induces a number of effects in cardiovascular system under normal and pathological conditions. In the present work, the effects and underlying mechanisms of the H2S donor sodium hydrosulfide (NaHS) on the isometric force of frog myocardium contraction have been studied. NaHS at the concentration of 100 μM induced negative inotropic effect and reduced the maximum velocity of the contraction and relaxation of the isolated ventricle strips. The substrate of H2S synthesis, L-cysteine (200 μM and 1 mM), induced the same effect, while the inhibitors of cystathionin-γ-lyase, the H2S-producing enzyme in heart, β-cyanoalanine (500 μM) and propargylglycine (500 μM), increased the amplitude of contraction. Inhibition of cystathionin-γ-lyase by β-cyanoalanine prevented the negative inotropic effect of L-cysteine. After the inhibition of adenylate cyclase by MDL-12,330A (3 μM) or phosphodiesterases by IBMX (200 μM), the effect of NaHS was less than that in the control. In the presence of membrane-penetrating analogous of cAMP, 8Br-cAMP (100 μM) and pCPT-cAMP (100 μM), the negative inotropic effect of NaHS was completely retained. The effect of NaHS significantly decreased after preliminary application of the NO donor, SNAP (10 μM), and did not change after the inhibition of NO synthases by L-NAME (100 μM). The results suggest the possibility of endogenous synthesis of H2S in frog myocardium and regulation of its contractility by the activation of phosphodiesterases hydrolyzing cAMP, which leads to a decrease in the activation of cAMP-dependent protein kinases and phosphorylation of voltage-dependent L-type Ca channels. As a result, the reduction of calcium entry into cardiomyocytes decreases the contractility of frog myocardium. © 2013 Pleiades Publishing, Ltd.

Experiments with selective agonists and antagonists of purinoceptors allowed us to evaluate the subtype of P2X receptors. We showed that the myocardium of 14-100-day-old rats contains functionally active P2X 1 receptors. These receptors are involved in the realization of the positive inotropic effect of the atria and ventricles. Selective P2X 1 receptor agonist β,γ-methylene-ATP induced a dose-dependent increase in the strength of atrial and ventricular contractions. P2X 1 receptor antagonist TNP-ATP abolished the effect of the agonist in rats of all age groups. © Springer Science+Business Media, Inc. 2008.

© 2019 Plant Archives. All rights reserved. In the present work, they studied the effect of the selective NPY1 agonist of Leu (31), Pro (34) -NPY receptors of different concentrations on the myocardial contractility of neonatal and adult rats. During analysis of the myocardial strip isometric contraction, they found that the agonist causes a dose-dependent changes of the myocardial strip contraction strength. Leu31, Pro34NPY in the concentration range of 10-7-10-5 M does not cause significant changes in the isometric contraction of the myocardial strips in the atria and ventricles among 7-day-old animals. Among 21-day-old animals, Leu31, Pro34NPY, at the concentration of 10-6 M, and the agonist (10-7 M) increases the force of contraction in the myocardium among 100-day-old animals.

© 2017, Springer Science+Business Media New York.Selective agonist (Leu(31)Pro(34)NPY) and blocker (BIBP-3226) of NPY1 receptors were used to determine the type of NPY receptors involved in myocardial contraction. Experiments with isometric contraction of myocardial strips from mature rats showed that the agonist produced the most potent effect in a concentration of 10—7 M. In this concentration, Leu(31)Pro(34)NPY showed the greatest positive inotropic effect on the contraction of the atria and ventricles. In contrast, selective blocker BIBP-3226 reduced the force of myocardial contractions. Pretreatment of myocardial strips with this blocker abolished the positive inotropic effect of Leu(31)Pro(34)NPY, which attested to important role of NPY1 receptors in myocardial contraction.

Experiments with R2Y receptor blockers allowed identification of R2Y subtypes mediating the inhibitory effects of uridine triphosphate on myocardial contractility. In 100-day-old animals, the myocardial inotropic response to the administration of uridine triphosphate was mediated by R2Y2 receptors. R2Y4 receptors took part in the realization of negative inotropic response to uridine triphosphate in all age groups, but the most pronounced effects of this substance on myocardial contractility were found in 100-day-old rats. It was found that R2Y receptor blockers PPADS and reagent blue-2 affect amplitude-time parameters of myocardial contractility in rats of various ages. © 2014 Springer Science+Business Media New York.

© 2014, Springer Science+Business Media New York. We studied the effect of neuropeptide Y in concentrations of 10–10-10–6 M on myocardial contractility of rats at the age of 7, 21, and 100 days. Studying the isometric contraction of myocardial strips showed that neuropeptide Y decreases the force of myocardial contraction in 7-day-old rat pups. Exogenous neuropeptide Y produced a biphasic effect in 21-day-old rats, which was manifested in the increase and subsequent decrease in myocardial contractility. Neuropeptide Y had little effect on myocardial contractility of 100-day-old animals.

© 2017, Springer Science+Business Media New York.Selective agonist (Leu(31)Pro(34)NPY) and blocker (BIBP-3226) of NPY1 receptors were used to determine the type of NPY receptors involved in myocardial contraction. Experiments with isometric contraction of myocardial strips from mature rats showed that the agonist produced the most potent effect in a concentration of 10—7 M. In this concentration, Leu(31)Pro(34)NPY showed the greatest positive inotropic effect on the contraction of the atria and ventricles. In contrast, selective blocker BIBP-3226 reduced the force of myocardial contractions. Pretreatment of myocardial strips with this blocker abolished the positive inotropic effect of Leu(31)Pro(34)NPY, which attested to important role of NPY1 receptors in myocardial contraction.

© 2014, Springer Science+Business Media New York. We studied the effect of neuropeptide Y in concentrations of 10–10-10–6 M on myocardial contractility of rats at the age of 7, 21, and 100 days. Studying the isometric contraction of myocardial strips showed that neuropeptide Y decreases the force of myocardial contraction in 7-day-old rat pups. Exogenous neuropeptide Y produced a biphasic effect in 21-day-old rats, which was manifested in the increase and subsequent decrease in myocardial contractility. Neuropeptide Y had little effect on myocardial contractility of 100-day-old animals.

Experiments with R2Y receptor blockers allowed identification of R2Y subtypes mediating the inhibitory effects of uridine triphosphate on myocardial contractility. In 100-day-old animals, the myocardial inotropic response to the administration of uridine triphosphate was mediated by R2Y2 receptors. R2Y4 receptors took part in the realization of negative inotropic response to uridine triphosphate in all age groups, but the most pronounced effects of this substance on myocardial contractility were found in 100-day-old rats. It was found that R2Y receptor blockers PPADS and reagent blue-2 affect amplitude-time parameters of myocardial contractility in rats of various ages. © 2014 Springer Science+Business Media New York.

Tato práce je věnována výpočtu a analýze parametrů srdeční funkce, které je možné stanovit z obrazových dat pořízených magnetickou rezonancí. Pro výpočet byly použity ručně anotované snímky pořízené v krátké srdeční ose. Objemové parametry byly dopočítány přímo z obrazových dat sečtením voxelů náležejícím k příslušným strukturám srdce a následným vynásobením objemem voxelu. Funkční parametry byly následně dopočítány dle oficiálních definic z objemových parametrů. Dále byla stanovena tloušťka stěny myokardu levé komory pomocí modifikované radiální metody a kontraktilita myokardu pomocí segmentální deformační analýzy. Výsledné hodnoty byly vyneseny do tabulky a zobrazeny box–ploty. Dále byla provedena korelační analýza a následná zkouška klasifikačního stromu na vypočtených datech., The thesis is focused on calculation and analysis of heart function parameters which could be calculated from image data obtained by magnetic resonance. Manually annotated image data in short axis of heart were used for calculation. Volumetric parameters were calculated directly from image data by counting voxels which were parts of specific heart structure and then multiplied by voxel volume. Modified radial method was used to compute functional parameters whereas myocardial contractility was calculated by using segmental strain analysis. Obtained results were given into table and visualised in box– plots. Correlation analysis of parameters was also performed and decision tree classifier was used to test discrimination capacity of estimated parameters.

Tato práce je věnována výpočtu a analýze parametrů srdeční funkce, které je možné stanovit z obrazových dat pořízených magnetickou rezonancí. Pro výpočet byly použity ručně anotované snímky pořízené v krátké srdeční ose. Objemové parametry byly dopočítány přímo z obrazových dat sečtením voxelů náležejícím k příslušným strukturám srdce a následným vynásobením objemem voxelu. Funkční parametry byly následně dopočítány dle oficiálních definic z objemových parametrů. Dále byla stanovena tloušťka stěny myokardu levé komory pomocí modifikované radiální metody a kontraktilita myokardu pomocí segmentální deformační analýzy. Výsledné hodnoty byly vyneseny do tabulky a zobrazeny box–ploty. Dále byla provedena korelační analýza a následná zkouška klasifikačního stromu na vypočtených datech., The thesis is focused on calculation and analysis of heart function parameters which could be calculated from image data obtained by magnetic resonance. Manually annotated image data in short axis of heart were used for calculation. Volumetric parameters were calculated directly from image data by counting voxels which were parts of specific heart structure and then multiplied by voxel volume. Modified radial method was used to compute functional parameters whereas myocardial contractility was calculated by using segmental strain analysis. Obtained results were given into table and visualised in box– plots. Correlation analysis of parameters was also performed and decision tree classifier was used to test discrimination capacity of estimated parameters.

Tato práce je věnována výpočtu a analýze parametrů srdeční funkce, které je možné stanovit z obrazových dat pořízených magnetickou rezonancí. Pro výpočet byly použity ručně anotované snímky pořízené v krátké srdeční ose. Objemové parametry byly dopočítány přímo z obrazových dat sečtením voxelů náležejícím k příslušným strukturám srdce a následným vynásobením objemem voxelu. Funkční parametry byly následně dopočítány dle oficiálních definic z objemových parametrů. Dále byla stanovena tloušťka stěny myokardu levé komory pomocí modifikované radiální metody a kontraktilita myokardu pomocí segmentální deformační analýzy. Výsledné hodnoty byly vyneseny do tabulky a zobrazeny box–ploty. Dále byla provedena korelační analýza a následná zkouška klasifikačního stromu na vypočtených datech., The thesis is focused on calculation and analysis of heart function parameters which could be calculated from image data obtained by magnetic resonance. Manually annotated image data in short axis of heart were used for calculation. Volumetric parameters were calculated directly from image data by counting voxels which were parts of specific heart structure and then multiplied by voxel volume. Modified radial method was used to compute functional parameters whereas myocardial contractility was calculated by using segmental strain analysis. Obtained results were given into table and visualised in box– plots. Correlation analysis of parameters was also performed and decision tree classifier was used to test discrimination capacity of estimated parameters.