Összesen 4 találat.


001-es BibID:BIBFORM024047
Első szerző:Bányász Tamás (élettanász)
Cím:Changes in cardiac contractility in IDDM and NIDDM diabetic rats / Bányász T., Kalapos I., Kelemen Sz., Kovács T.
Megjegyzések:Differences in myocardial contractility were studied in type I (insulin-dependent, IDDM) and type II (non-insulin-dependent, NIDDM) diabetic rats. Using the streptozotocin-induced diabetes as an experimental model, the contractile properties of left ventricular myocardium of IDDM and NIDDM animals were compared to similar parameters of their age-matched controls. Contraction force was analyzed as a function of the pacing frequency. Paired-pulse stimulation and catecholamine treatment were applied to compare the inotropic responses obtained in the two types of diabetes. Diabetic and control preparations developed equal peak tension at each driving frequency upon the application of paired-pulse stimulation with fixed interpulse interval. The interpulse interval dependence of paired-pulse induced inotropy was altered and the velocity of contraction and relaxation decreased in IDDM, but not in NIDDM muscles. Sensitivity to isoproterenol and norepinephrine was decreased in both types of diabetes, however, the isoproterenol resistance of old diabetic animals was attributable to age rather than to the diabetic state. The results indicate that alterations in the contractile parameters and catecholamine sensitivity in IDDM differ from those observed in NIDDM form of diabetes mellitus.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:General Physiology And Biophysics 15 : 5 (1996), p. 357-369. -
További szerzők:Kalapos István (1954-) (orvos, élettanász) Kelemen Sz. Kovács T.
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001-es BibID:BIBFORM016887
Első szerző:Bárándi László (élettanász)
Cím:Drug-induced changes in action potential duration are proportional to action potential duration in rat ventricular myocardium / Bárándi, L., Harmati, G., Horváth, B., Szentandrássy, N., Magyar, J., Varró, A., Nánási, P.P., Bányász, T.
Megjegyzések:Several cardioactive agents exhibit direct or reverse rate-dependent effects on action potential duration (APD) depending on the experimental conditions. Recently, a new theory has been proposed, suggesting that the reverse rate-dependent mode of drug-action may be a common property of canine, rabbit, guinea pig and human cardiac tissues, and this phenomenon is based on the dependence of drug-action on baseline APD. The aim of the present work was to examine the limitations of this hypothesis by studying the APD lengthening effect of K+ channel blockers and the APD shortening effect of Ca2+ channel blockers during the electrical restitution process of rat ventricular action potentials. Rat ventricular muscle was chosen because it has a set of ion currents markedly different from those of other species, its APD is shorter by one order of magnitude than that of the "plateau-forming" larger mammals, and most importantly, its APD increases at higher heart rates ? opposite to many other species. The restitution of APD was studied as a function of the diastolic interval, a parameter indicating the proximity of action potentials. It was found that drug-induced APD changes in rat myocardium are proportional with the pre-drug value of APD but not with the diastolic interval, indicating that not the proximity of consecutive action potentials, but the baseline APD itself may determine the magnitude of drug-induced APD changes.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Action potential duration
Electrical restitution
Membrane current
Reverse rate dependence
Ventricular repolarization
Megjelenés:General Physiology And Biophysics. - 29 : 3 (2010), p. 309-313. -
További szerzők:Harmati Gábor (1983-) (élettanász) Horváth Balázs (1981-) (élettanász) Szentandrássy Norbert (1976-) (élettanász) Magyar János (1961-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász) Bányász Tamás (1960-) (élettanász)
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001-es BibID:BIBFORM030260
035-os BibID:WOS:000187507900005
Első szerző:Fülöp László (kardiológus)
Cím:The role of transmembrane chloride current in afterdepolarisations in canine ventricular cardiomyocytes / L. Fülöp, E. Fiák, N. Szentandrássy, J. Magyar, P. P. Nánási, T. Bányász
Megjegyzések:The physiological role of chloride currents (I-Cl) in cardiac cells is poorly understood. The aim of the present study was to reveal the role of I-Cl in the genesis of early and delayed afterdepolarisations (EADs and DADs, respectively). First we identified I-Cl under action potential voltage clamp conditions as the anthracene-9-carboxylic acid (ANTRA) (0.5 mmol/l)-sensitive current. The ANTRA-sensitive current was large and outwardly directed at the beginning, while it was moderate and inwardly directed at the end of the action potential. Application of ANTRA under current clamp conditions decreased the depth of the incisura, shifted the plateau upwards and lengthened the duration of action potentials. The effect of ANTRA was studied in three models of afterdepolarisations: the ouabain-induced DAD model, the caesium-induced EAD model, and in the presence of subthreshold concentration of isoproterenol. Preincubation of the cells with 0.5 mmol/l ANTRA failed to induce afterdepolarisations. Ouabain (200 nmol/l) alone caused DADs in 62.5 % of the cells within 15 min. When ouabain was applied in the presence of ANTRA, 60 % of the myocytes transiently displayed EADs before the development of DADs, and all cells developed DADs within 7 min. Isoproterenol (5 nmol/l) alone failed to induce afterdepolarisations. However, 75 % of the cells produced DADs within 6 min when superfused with isoproterenol in the presence of ANTRA. Incubation of the myocytes with 3.6 mmol/l CsCl caused EADs in 71.4 % of the cells within 30 min. Application of CsCl in the presence of ANTRA resulted in immediate depolarisation of the membrane from -79.6 +/- 0.4 to -54.2 +/- 3.5 mV. Summarizing our results we conclude that the ANTRA-sensitive current is an important mechanism of defence against afterdepolarisations. Suppression of I-Cl may thus increase the incidence and accelerate the rate of development of both EADs and DADs.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:General Physiology and Biophysics. - 22 : 3 (2003), p. 341-353. -
További szerzők:Fiak Edit Szentandrássy Norbert (1976-) (élettanász) Magyar János (1961-) (élettanász) Nánási Péter Pál (1956-) (élettanász) Bányász Tamás (1960-) (élettanász)
Internet cím:Intézményi repozitóriumban (DEA) tárolt változat


001-es BibID:BIBFORM063951
Első szerző:Magyar János (élettanász)
Cím:Concept of relative variability of cardiac action potential duration and its test under various experimental conditions / János Magyar, Kornél Kistamás, Krisztina Váczi, Bence Hegyi, Balázs Horváth, Tamás Bányász, Péter P. Nánási, Norbert Szentandrássy
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:General Physiology and Biophysics. - 35 : 1 (2016), p. 55-62. -
További szerzők:Kistamás Kornél (1986-) (biológus) Váczi Krisztina (1987-) (élettanász) Hegyi Bence (1987-) (élettanász) Horváth Balázs (1981-) (élettanász) Bányász Tamás (1960-) (élettanász) Nánási Péter Pál (1956-) (élettanász) Szentandrássy Norbert (1976-) (élettanász)
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