A szív repolarizációs folyamatának celluláris szintű élettani, kórélettani és farmakológiai vizsgálata = Physiological, pathophysiological and pharmacological study of the cardiac repolarization

Kísérleteink során a szívizom repolarizációjával és a repolarizációs rezerv szerepével foglalkoztunk. Vizsgálataink szerint az IKs kulcsfontosságú szerepe van a repolarizációs rezerv kialakításában. Bizonyítottuk, hogy experimentális diabéteszben az IKs és Ito káliumáramok downregulációja miatt a repolarizációs rezerv beszűkül, és ennek vélhetően megnövekedett proaritmiás kockázat lehet a következménye. Új in vivo módszert dolgoztunk ki, amely lehetővé teszi a csökkent repolarizációs rezerv megítélést és alkalmas lehet a kórfolyamatok és gyógyszer proaritmiás hatásainak előrejelzésére. Molekuláris biológiai kísérleteink szerint emberi szívizomban az Ito áram kialakításában az eddigi vélekedésektől eltérően más alfa egységek is meghatározzák. Ezen munkánkat 9 in extenzo angol nyelvű közleményben foglaltuk össze, melyek kummulatív impakt faktora 34.61. | We studied the nature of cardiac repolarization and the function of the repolarization reserve in cellular. In spite of IKs plays little role on normal repolarization it has a key role establishing the repolarization reserve. In experimental diabetes due to downregulation of IKs and Ito the repolarization reserve decreased which probably is associated with increased proarrhythmic risk. We developed a new in vivo method which is suitable to investigate the repolarization reserve and to predict the possible increased proarrhythmic risk in pathophysiological situation or after drug applications. Our molecular biological experiments rereated that in addition to the knew proteins other previously unrecognized alfa subunits contribute to the transmembrane ion channels conducting Ito. The results obtained during the granting period was published in 9 English papers (IF= 34.61)

What have we learned from two-pore potassium channels? Their molecular configuration and function in the human heart

Two-pore domain potassium channels (K2P) control excitability, stabilize the resting membrane potential below firing threshold, and accelerate repolarisation in different cells. Until now, fifteen different genes for the six K2P channel subfamily were cloned. The pore-forming part is translated from two genes and they are built up from a dimer of two two-unit transmembrane domains functioning with a wide spectrum of physiological profiles. K2P ion channels were discovered in the last two decades and gave novel opportunity to recognize the complex molecular mechanism of the potassium ion flux, and may lead to the design of individual drug targeting in the future. In this review, we summarise the structure, function, channelopathies and pharmacological silhouette of the two-pore potassium channels in the human tissues. In addition, we present the computer model of the partially reconstructed wild type K2P1/TWIK1 lacking the intracellular C and N terminal loop

Activation of the Poly(ADP-Ribose) Polymerase Pathway in Human Heart Failure

Poly(ADP-ribose) polymerase (PARP) activation has been implicated in the pathogenesis of acute and chronic myocardial dysfunction and heart failure. The goal of the present study was to investigate PARP activation in human heart failure, and to correlate PARP activation with various indices of apoptosis and oxidative and nitrosative stress in healthy (donor) and failing (NYHA class III–IV) human heart tissue samples. Higher levels of oxidized protein end-products were found in failing hearts compared with donor heart samples. On the other hand, no differences in tyrosine nitration (a marker of peroxynitrite generation) were detected. Activation of PARP was demonstrated in the failing hearts by an increased abundance of poly-ADP ribosylated proteins. Immunohistochemical analysis revealed that PARP activation was localized to the nucleus of the cardiomyocytes from the failing hearts. The expression of full-length PARP-1 was not significantly different in donor and failing hearts. The expression of caspase-9, in contrast, was significantly higher in the failing than in the donor hearts. Immunohistochemical analysis was used to detect the activation of mitochondrial apoptotic pathways. We found no significant translocation of apoptosis-inducing factor (AIF) into the nucleus. Overall, the current data provide evidence of oxidative stress and PARP activation in human heart failure. Interventional studies with antioxidants or PARP inhibitors are required to define the specific roles of these factors in the pathogenesis of human heart failure