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001-es BibID:BIBFORM030250
035-os BibID:WOS:000182475600002
Első szerző:Fülöp László (kardiológus)
Cím:Differences in electrophysiological and contractile properties of mammalian cardiac tissues bathed in bicarbonate - and HEPES-buffered solutions / L. Fülöp, G. Szigeti, J. Magyar, N. Szentandrássy, T. Ivanics, Z. Miklós, L. Ligeti, A. Kovács, G. Szénási, L. Csernoch, P. P. Nánási, T. Bányász
Dátum:2003
ISSN:0001-6772
Megjegyzések:Aim: The aim of this study was to compare the action potential configuration, contractility, intracellular Ca2+ and H+ concentrations in mammalian cardiac tissues bathed with Krebs and Tyrode solutions at 37 degreesC. Results: In Langendorff-perfused guinea-pig hearts, loaded with the fluorescent Ca2+ -indicator Fura-2, or H+ -sensitive dye carboxy-SNARF, shifts from Krebs to Tyrode solution caused intra-cellular acidification, increased diastolic pressure and [Ca2+ ](i) , decreased systolic pressure and [Ca2+ ](i) , leading to a reduction in the amplitude of [Ca2+ ](i) transients and pulse pressure. Contractility was also depressed in canine ventricular trabeculae when transferred from Krebs to Tyrode solution. Shifts from Krebs to Tyrode solution increased the duration of action potentials in multicellular cardiac preparations excised from canine and rabbit hearts but not in isolated cardiomyocytes. All these changes in action potential morphology, contractility, [Ca2+ ](i) and [H+ ](i) were readily reversible by addition of 26 mmol L-1 bicarbonate to Tyrode solution. Effects of dofetilide and CsCl, both blockers of the delayed rectifier K current, on action potential duration were compared in Krebs and Tyrode solutions. Dofetilide lengthened rabbit ventricular action potentials in a significantly greater extent in Tyrode than in Krebs solution. Exposure of canine Purkinje fibres to CsCl evoked early after depolarizations within 40 min in all preparations incubated with Tyrode solution, but not in those bathed with Krebs solution. Conclusion: It is concluded that the marked differences in action potential morphology, [Ca2+ ](i) , [H+ ](i) and contractility observed between preparations bathed with Krebs and Tyrode solutions are more likely attributable to differences in the intracellular buffering capacities of the two media.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Acta Physiologica Scandinavica. - 178 : 1 (2003), p. 11-18. -
További szerzők:Szigeti Gyula (1969-) (élettanász, elektrofiziológus) Magyar János (1961-) (élettanász) Szentandrássy Norbert (1976-) (élettanász) Ivanics Tamás Miklós Zsuzsanna Ligeti László Kovács A. Szénási Gábor Csernoch László (1961-) (élettanász) Nánási Péter Pál (1956-) (élettanász) Bányász Tamás (1960-) (élettanász)
Internet cím:DOI
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2.

001-es BibID:BIBFORM030248
035-os BibID:WOS:000187850300006
Első szerző:Fülöp László (kardiológus)
Cím:Reopening of L-type calcium channels in human ventricular myocytes during applied epicardial action potentials / L. Fülöp, T. Bányász, J. Magyar, N. Szentandrássy, A. Varró, P. P. Nánási
Dátum:2004
ISSN:0001-6772
Megjegyzések:Aims: Present study was performed to compare the dynamics of human L-type calcium current (I-Ca,I-L) flowing during rectangular voltage pulses, voltage ramps, and action potentials (APs) recorded from epicardiac and endocardiac canine ventricular cells. Methods: I-Ca,I-L was recorded in single myocytes isolated from undiseased human hearts using the whole cell voltage clamp technique. Results: The decay of I-Ca,I-L was monotonic when using rectangular pulses or endocardial APs as voltage commands, whereas the current became double-peaked (displaying a second rise and fall) during epicardial (EPI) APs or voltage ramps used to mimic EPI APs. These I-Ca,I-L profiles were associated with single-hooked and double-hooked phase-plane trajectories, respectively. No sustained current was observed during the AP commands. Kinetics of deactivation and recovery from inactivation of human I-Ca,I-L were determined using twin-pulse voltage protocols and voltage ramps, and the results were similar to those obtained previously in canine cells under identical experimental conditions. Conclusions: I-Ca,I-L can inactivate partially before and deactivate during the phase-1 repolarization of the epicardiac AP, and reopening of these channels seems to be associated with formation of the dome.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Acta Physiologica Scandinavica. - 180 : 1 (2004), p. 39-47. -
További szerzők:Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Szentandrássy Norbert (1976-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
Internet cím:DOI
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3.

001-es BibID:BIBFORM030276
035-os BibID:WOS:000074327800003
Első szerző:Szigligeti Péter
Cím:Intracellular calcium and electrical restitution in mammalian cardiac cells / P. Szigligeti, T. Banyasz, J. Magyar, Gy. Szigeti, Z. Papp, A. Varro, P. P. Nanasi
Dátum:1998
ISSN:0001-6772
Megjegyzések:The role of calcium current and changes in intracellular calcium concentration ([Ca(2+)](i)) in regulation of action potential duration (APD) during electrical restitution process was studied in mammalian ventricular preparations. Properly timed action potentials were recorded from multicellular preparations and isolated cardiomyocytes using conventional microelectrodes and EGTA-containing patch pipettes, APD increased monotonically in canine and guinea pig ventricular preparations with increasing diastolic interval (DI), while in rabbit papillary muscles the restitution process was biphasic: APD first lengthened, then shortened as the DI increased. When the restitution process was studied in single cardiomyocytes using EGTA-containing patch pipettes, the restitution pattern was similar in the three species studied. Similarly, no difference was observed in the recovery time constant of calcium current (/(Ca-L)) measured under these conditions in voltage clamped myocytes. Loading the myocytes with the [Ca(2+)](i)-chelator BAPTA-AM had adverse effects in rabbit and canine cells. In rabbit myocytes steady-state APD lengthened and the late shortening component of restitution was abolished in BAPTA-loaded cells. In canine myocytes BAPTA-load shortened steady-stare APD markedly, and during restitution, APD decreased with increasing DI. The late shortening component of restitution, observed in untreated rabbit preparations, was greatly reduced after nifedipine treatment, but remained preserved in the presence of 4-aminopyridine or nicorandil. Beat to beat changes in APD, peak /Ca-L and [Ca(2+)](i), measured using the fluorescent dye, Fura-2, were monitored in rabbit ventricular myocytes after a 1-min period of rest. In these cells, the shortening of APD was accompanied by a gradual reduction of the peak /Ca-L and elevation of diastolic [Ca(2+)](i) during the initial eight post-rest action potentials. it is concluded that elevation of [Ca(2+)](i) shortens, while reduction of [Ca(2+)](i) lengthens APD in rabbit, but not in canine ventricular myocytes. These differences may probably be related.io different distributions of [Ca(2+)](i)-dependent ion currents and/or to differences in calcium handling between the two species.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Acta Physiologica Scandinavica. - 163 : 2 (1998), p. 139-147. -
További szerzők:Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Szigeti Gyula (1969-) (élettanász, elektrofiziológus) Papp Zoltán (1965-) (kardiológus, élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat
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