Összesen 4 találat.


001-es BibID:BIBFORM049664
Első szerző:Magyar János (élettanász)
Cím:SEA0400 Fails To Alter The Magnitude Of Intracellular Ca2+ Transients And Contractions In Guinea Pig Heart / János Magyar, Norbert Szentandrássy, Péter Birinyi, Attila Farkas, András Tóth, László Csernoch, András Varró, Péter P. Nánási
Tárgyszavak:Orvostudományok Elméleti orvostudományok idézhető absztrakt
Megjelenés:Biophysical Journal. - 96 : 3 (2009), p. 512a. -
További szerzők:Szentandrássy Norbert (1976-) (élettanász) Birinyi Péter (1981-) (élettanász) Farkas Attila (1961-) (farmakológus) Tóth András (farmakológus) Csernoch László (1961-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
Internet cím:Szerző által megadott URL
Intézményi repozitóriumban (DEA) tárolt változat


001-es BibID:BIBFORM053175
035-os BibID:WOS:000326116400010
Első szerző:Nagy Norbert (kísérletes farmakológus)
Cím:[Ca2+]i-induced augmentation of the inward rectifier potassium current (IK1) in canine and human ventricular myocardium / Norbert Nagy, Károly Acsai, Anita Kormos, Zsuzsanna Sebők, Attila S. Farkas, Norbert Jost, Péter P. Nánási, Julius Gy. Papp, András Varró, András Tóth
Megjegyzések:The inward rectifier K? current (IK1) plays an important role in terminal repolarization and stabilization of the resting potential in cardiac cells. Although IK1 was shown to be sensitive to changes in intracellular Ca?? concentration ([Ca??]i), the nature of this Ca?? sensitivity-in spite of its deep influence on action potential morphology-is controversial. Therefore, we aimed to investigate the effects of a nonadrenergic rise in [Ca??]i on the amplitude of IK1 in canine and human ventricular myocardium and its consequences on cardiac repolarization. IK1, defined as the current inhibited by 10 ?M Ba??, was significantly increased in isolated canine myocytes following a steady rise in [Ca??]i. Enhanced IK1 was also observed when [Ca??]i was not buffered by ethylene glycol tetraacetic acid, and [Ca??]I transients were generated. This [Ca??]i-dependent augmentation of IK1 was largely attenuated after inhibition of CaMKII by 1 ?M KN-93. Elevation of [Ca??]o in multicellular canine and human ventricular preparations resulted in shortening of action potentials and acceleration of terminal repolarization. High [Ca??]o enhanced the action potential lengthening effect of the Ba(2+)-induced IK1 blockade and attenuated the prolongation of action potentials following a 0.3-?M dofetilide-induced IKr blockade. Blockade of IKs by 0.5 ?M HMR-1556 had no significant effect on APD90 in either 2 mM or 4 mM [Ca??]o. It is concluded that high [Ca??]i leads to augmentation of the Ba??-sensitive current in dogs and humans, regardless of the mechanism of the increase. This effect seems to be at least partially mediated by a CaMKII-dependent pathway and may provide an effective endogenous defense against cardiac arrhythmias induced by Ca?? overload.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Canine/human myocardium
Inward rectifier K+ current (IK1)
Cytosolic Ca2+
Action potential duration
Ventricular repolarization
Megjelenés:Pflugers Archiv-European Journal of Physiology. - 465 : 11 (2013), p. 1621-1635. -
További szerzők:Acsai Károly Kormos Anita Sebők Zsuzsanna Farkas Attila (1961-) (farmakológus) Jost Norbert Nánási Péter Pál (1956-) (élettanász) Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus) Tóth András (farmakológus)
Internet cím:Szerző által megadott URL
Intézményi repozitóriumban (DEA) tárolt változat


001-es BibID:BIBFORM009105
Első szerző:Nagy Norbert (kísérletes farmakológus)
Cím:Does small-conductance calcium-activated potassium channel contribute to cardiac repolarization? / Nagy, N., Szuts, V., Horvath, Z., Seprenyi, G., Farkas, A. S., Acsai, K., Prorok, J., Bitay, M., Kun, A., Pataricza, J., Papp, J. G., Nanasi, P. P., Varro, A., Toth, A.
ISSN:0022-2828 (Print)
Megjegyzések:Small-conductance calcium-activated potassium channels (SK channels) have a significant role in neurons. Since they directly integrate calcium handling with repolarization, in heart their role would be particularly important. However, their contribution to cardiac repolarization is still unclear. A previous study reported a significant lengthening effect of apamin, a selective SK channel inhibitor, on the action potential duration in atrial and ventricular mouse cardiomyocytes and human atrial cells. They concluded that these channels provide an important functional link between intracellular calcium handling and action potential kinetics. These findings seriously contradict our studies on cardiac "repolarization reserve", where we demonstrated that inhibition of a potassium current is not likely to cause excessive APD lengthening, since its decrease is mostly compensated by a secondary increase in other, unblocked potassium currents. To clarify this contradiction, we reinvestigated the role of the SK current in cardiac repolarization, using conventional microelectrode and voltage-clamp techniques in rat and dog atrial and ventricular multicellular preparations, and in isolated cardiomyocytes. SK2 channel expression was confirmed with immunoblot technique and confocal microscopy. We found, that while SK2 channels are expressed in the myocardium, a full blockade of these channels by 100 nM apamin--in contrast to the previous report--did not cause measurable electrophysiological changes in mammalian myocardium, even when the repolarization reserve was blunted. These results clearly demonstrate that in rat, dog and human ventricular cells under normal physiological conditions--though present--SK2 channels are not active and do not contribute to action potential repolarization.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of Molecular and Cellular Cardiology. - 47 : 5 (2009), p. 656-663. -
További szerzők:Szűts Viktória (farmakológus Szeged) Horváth Zoltán Seprényi György Farkas Attila (1961-) (farmakológus) Acsai Károly Prorok János Bitay Miklós Kun Attila Pataricza János Papp Gy. Julius (Szeged) Nánási Péter Pál (1956-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Tóth András (farmakológus)
Internet cím:DOI
elektronikus változat


001-es BibID:BIBFORM004111
Első szerző:Szentandrássy Norbert (élettanász)
Cím:SEA0400 fails to alter the magnitude of intracellular Ca2+ transients and contractions in Langendorff-perfused guinea pig hearts / Szentandrássy N., Birinyi P., Szigeti Gy., Farkas A., Magyar J., Tóth A., Csernoch L., Varró A., Nánási P.P.
Megjegyzések:SEA0400 is a recently developed inhibitor of the Na+/Ca2+ exchanger (NCX) shown to suppress both forward and reverse mode operation of NCX. Present experiments were designed to study the effect of partial blockade of NCX on Ca handling and contractility in Langendorff-perfused guinea pig hearts loaded with the fluorescent Ca-sensitive dye fura-2. Left ventricular pressure and intracellular calcium concentration ([Ca2+]i) were synchronously recorded before and after cumulative superfusion with 0.3 and 1 muM SEA0400. SEA0400 caused no significant change in the systolic and diastolic values of left ventricular pressure and [Ca2+]i. Accordingly, pulse pressure and amplitude of the [Ca2+]i transient also remained unchanged in the presence of SEA0400. SEA0400 had no influence either on the time required to reach peak values of pressure and [Ca2+)]i or on half relaxation time. On the other hand, both 0.3 and 1 microM SEA0400 significantly increased the decay time constant of [Ca2+]i transients, obtained by fitting its descending limb between 30% and 90% of relaxation, from 127 +/- 7 to 165 +/- 7 and 177 +/- 14 ms, respectively (P < 0.05, n=6). In contrast to the guinea pig hearts, rat hearts responded to SEA0400 treatment with increased [Ca2+]i transients and contractility. These interspecies differences observed in the effect of SEA0400 can be explained by the known differences in calcium handling between the two species.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Naunyn-Schmiedeberg's Archives of Pharmacology. - 378 : 1 (2008), p. 65-71. -
További szerzők:Birinyi Péter (1981-) (élettanász) Szigeti Gyula (1969-) (élettanász, elektrofiziológus) Farkas Attila (1961-) (farmakológus) Magyar János (1961-) (élettanász) Tóth András (farmakológus) Csernoch László (1961-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
Internet cím:elektronikus változat
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