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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 Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM030257
035-os BibID:	WOS:000169039300004
Első szerző:	Magyar János (élettanász)
Cím:	Effects of the antiarrhythmic agent EGIS-7229 (S 21407) on calcium and potassium currents in canine ventricular cardiomyocytes / János Magyar, Tamás Bányász, László Fülöp, Norbert Szentandrássy, Ágnes Körtvély, Anikó Kovács, Gábor Szénási, Péter P. Nánási
Dátum:	2001
ISSN:	0028-1298
Megjegyzések:	Based on earlier pharmacological studies performed using conventional microelectrodes EGIS-7229 (S 21407), the novel antiarrhythmic candidate, was suggested to have a combined mode of action in cardiac tissues isolated from various mammalian species. In order to characterize the electrophysiological effects of the compound, its effects on calcium and potassium currents of isolated canine ventricular cardiomyocytes were studied in the present work using the whole cell configuration of the patch clamp technique. L-type Ca current (I-Ca) was significantly depressed by EGIS-7229 at concentrations of 3 muM or higher with no concomitant changes in the voltage-dependence of activation and time course of inactivation of I-Ca. The drug reversibly suppressed the rapid component of the delayed rectifier K current (I-Kr) in a concentration-dependent manner, having a K-0.5 value of 1.1+/-0.1 muM and a slope factor of close to unity (1.23+/-0.16), indicating that probably one single binding site of high affinity may be involved in binding of EGIS-7229 to the I-Kr channel. In contrast, no changes in the slow component of the delayed rectifier K current (I-Ks,) was observed with the compound up to the concentration of 100 muM, even if the current was fully activated by 8-bromo-cAMP. At a concentration of 10 muM or higher, EGIS-7229 caused also a moderate but significant reduction in the inward rectifier K current (I-K1) and the transient outward K current (I-to) with no change in the voltage-dependence of activation and steady-state inactivation of I-to. Present results indicate that EGIS-7229 can be considered as a selective I-Kr blocker at low (1 muM) concentration; however, its combined (class III + IV) mechanism of action is evident at concentrations of 3 muM or higher. Suppression of I-Ca may explain the lack of development of early afterdepolarizations in the presence of EGIS-7229, predicting a relatively safe clinical application in contrast to pure class III compounds.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban egyetemen (Magyarországon) készült közlemény
Megjelenés:	Naunyn-Schmiedebergs Archives of Pharmacology. - 363 : 6 (2001), p. 604-611. -
További szerzők:	Bányász Tamás (1960-) (élettanász) Fülöp László (1976-) (kardiológus) Szentandrássy Norbert (1976-) (élettanász) Körtvély Ágnes Kovács Anikó Szénási Gábor Nánási Péter Pál (1956-) (élettanász)
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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Saját polcon: