Studies on the role of disturbed Ca2+ homeostasis in the pathomechanism of the cardiac effects of experimental diabetes using conventional and novel experimental techniques
The Na+/Ca2+exchanger (NCX) plays a crucial role in cardiac electrophysiology via maintaining ionic distributions between the cytoplasm and the extracellular space, shaping the action potential and modulating the contractile activity of the heart viatight regulation of the cytoplasmic[Ca2+]. Since t...
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| Dokumentumtípus: | Disszertáció |
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2014-04-29
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| doi: | 10.14232/phd.2199 |
| mtmt: | 2782508 |
| Online Access: | http://doktori.ek.szte.hu/2199 |
| Tartalmi kivonat: | The Na+/Ca2+exchanger (NCX) plays a crucial role in cardiac electrophysiology via maintaining ionic distributions between the cytoplasm and the extracellular space, shaping the action potential and modulating the contractile activity of the heart viatight regulation of the cytoplasmic[Ca2+]. Since the NCX is the primary transporter to extrude Ca2+from the cells, both the Ca2+content of the cardiomyocytes and magnitude and kinetics of the intracellular Ca2+-transient during action potential are highly dependent on its expression level and functional activity. In spite of its critical function, a relatively selective pharmacological NCX inhibitor (SEA0400) has only recently become available, offering yet unexplored novel possibilities in studying NCX function and malfunction. In our first experimental study we aimed to evaluate the effects of selective, partial NCX inhibition by SEA0400 on Ca2+handling in isolated canine ventricular myocytes.Since the origin and progression of the pathomechanisms, leading to diabetes-induced cardiomyopathy, are poorly explored, monitoring diabetes induced changes in intracellular Ca2+handling in cardiomyocytes in various functional states may help us to improve our rather limited understanding of the pathophysiology of diabetes-associated heart diseases. This improvement, in turn, may open much needed novel therapeutic avenues for more effective prevention and early treatment of cardiac complications in diabetic patients. In our second study we aimed to investigate in an experimental animal model of Type 1 diabetes the putative perturbations in NCX function, by monitoring shifts in intracellular [Ca2+], following the applicationof the selective NCX inhibitorSEA0400.The final part of the present thesis describes a promising methodological work. Virus-mediated gene transfer has recently become an important tool for introduction of recombinant genes into cardiomyocytes, offering the potential to treat both rare and common cardiac disorders. In our third study we have developed a novel, pseudorabies virusvector (PRV)-based technique, which enables the targeted delivery of genetically encoded activity sensors into primary culture of isolated adult canine cardiomyocytes. This system has several advantageous features: 1) the virus enters the cells without destroying the intact physiological properties of the cells for a prolonged period; 2) the virus had no effect on the observed physiological properties. We have shown for the first time, that novel herpesvirus-based vectors can efficiently transduce genes into non-dividing cardiac myocytes, offering an alternative approach for gene transfer in this fastidious experimental object. |
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