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1.

001-es BibID:BIBFORM032954
Első szerző:Bányász Tamás (élettanász)
Cím:Frequency-dependent characteristics of human cardiac muscle / Tamás Bányász, János Magyar, Péter Szigligeti, Csaba Pankucsi, András Varró, Péter P. Nánási
Dátum:1997
Megjegyzések:OBJECTIVES: To characterize the steady state frequency-dependent properties and restitution kinetics of action potential duration (APD) in isolated human atrial and ventricular cardiac muscle preparations. MATERIALS AND METHODS: Conventional microelectrode techniques were used to record action potentials in preparations of human left ventricular muscle and right atrial appendages under steady state conditions or after abrupt changes in cycle length, ie, following increasingly longer diastolic intervals (DI). Restitution relations were generated by plotting APD against the respective DI. Restitution relations were fitted to multiexponential functions. RESULTS: Restitution of APD at 90% repolarization in ventricular preparations, paced at a basic cycle length (BCL) of 750 ms, were fitted as the sum of four exponentials, having time constants of 42.8 ms, 139 ms, 1.34 s and 16 s. Similar results were obtained for restitution of values of APD at 50% repolarization. In atrial preparations, restitution kinetics were characterized by three exponentials with time constants of 154 ms, 1.52 s and 25.5 s (BCL of 750 ms). The very fast component of restitution, observed in ventricular muscle, was apparently missing in atrial fibres. When atrial preparations were paced at a longer BCL of 5000 ms, no change in time constants of restitution was observed; however, the amplitudes of the second and third atrial components decreased significantly compared with preparations paced at a BCL of 750 ms. CONCLUSIONS: Comparing the time constant values estimated for restitution with the reported kinetic parameters of cardiac ion channels, it may be speculated that the first component of restitution in ventricular muscle is attributed to the recovery of L-type calcium current from inactivation. The lack of this very rapid component in atrial muscle can be explained by the parallel recovery of the calcium current and the transient outward potassium current, prominent in atrial myocardium. The second ventricular component (first in atrium) may be due to the time-dependent deactivation of the delayed rectifier potassium current. The third and fourth ventricular components (second and third components, respectively, in the atrium) are probably related to transient changes in intracellular ionic composition.
Tárgyszavak:Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Experimental And Clinical Cardiology 2 : 3 (1997), p. 205-209. -
További szerzők:Magyar János (1961-) (élettanász) Szigligeti Péter Pankucsi Csaba (farmakológus) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
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2.

001-es BibID:BIBFORM030253
Első szerző:Bányász Tamás (élettanász)
Cím:Different effects of endothelin-1 on calcium and potassium currents in canine ventricular cells / Tamás Bányász, János Magyar, Ágnes Körtvély, Gyula Szigeti, Péter Szigligeti, Zoltán Papp, Attila Mohácsi, László Kovács, Péter P. Nánási
Dátum:2001
ISSN:0028-1298
Megjegyzések:Effects of endothelin-l (ET-1) on the L-type calcium current (I-Ca) and delayed rectifier potassium current (I-K) were studied in isolated canine ventricular cardiomyocytes using the whole-cell configuration of the patch-clamp technique. ET-1 (8 nM) was applied in three experimental arrangements: untreated cells, in the presence of 50 nM isoproterenol, and in the presence of 250 muM 8-bromo-cAMP. In untreated cells, ET-1 significantly decreased the peak amplitude of I-Ca by 32.3 +/-4.8% at +5 mV (P<0.05) without changing activation or inactivation characteristics of I-Ca. ET-1 had no effect on the amplitude of I-K, I-to (transient outward current) or I-K1 (inward rectifier K current) in untreated cells; however, the time course of recovery from inactivation of I-to was significantly increased by ET-1 (from 26.5<plus/minus>6 ms to 59.5 +/- 1.8 ms, P<0.05). Amplitude and time course of intracellular calcium transients, recorded in voltage-clamped cells previously loaded with the fluorescent calcium indicator dye Fura-2, were not affected by ET-1. ET-1 had no effect on force of contraction in canine ventricular trabeculae. Isoproterenol increased the amplitude of I-Ca to 263<plus/minus> 29% of control. ET-1 reduced I-Ca also in isoproterenol-treated cells by 17.8 +/-2% (P<0.05); this inhibition was significantly less than obtained in untreated cells. I-K was increased by isoproterenol to 213<plus/minus>18% of control. This effect of isoproterenol on I-K was reduced by 31.8 +/-4.8% if the cells were pretreated with ET-1. Similarly, in isoproterenol-treated cells ET-1 decreased I-K by 16.2 +/-1.5% (P<0.05). Maximal activation of protein kinase A (PKA) was achieved by application of 8-bromo-cAMP in the pipette solution. In the presence of 8-bromo-cAMP ET-l failed to alter I-CA or I-K It was concluded that differences in effects of ET-1 on I-CA and I-K may be related to differences in cAMP sensitivity of the currents.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Naunyn-Schmiedebergs Archives of Pharmacology. - 363 : 4 (2001), p. 383-390. -
További szerzők:Magyar János (1961-) (élettanász) Körtvély Ágnes Szigeti Gyula (1969-) (élettanász, elektrofiziológus) Szigligeti Péter Papp Zoltán (1965-) (kardiológus, élettanász) Mohácsi Attila (1960-) (orvos) Kovács László (1939-) (élettanász) Nánási Péter Pál (1956-) (élettanász)
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3.

001-es BibID:BIBFORM030263
035-os BibID:WOS:000168774300010
Első szerző:Jednákovits Andrea
Cím:In vivo and in vitro acute cardiovascular effects of bimoclomol / Andrea Jednákovits, Péter Ferdinándy, László Jaszlits, Tamás Bányász, János Magyar, Péter Szigligeti, Ágnes Körtvély, József A. Szentmiklósi, Péter P. Nánási
Dátum:2000
ISSN:0306-3623
Megjegyzések:Effects of bimoclomol, the novel heat shock protein (HSP) coinducer, was studied in various mammalian cardiac and rabbit aortic preparations. Bimoclomol decreased the ST-segment elevation induced by coronary occlusion in anesthetized dogs (56% and 80% reduction with 1 and 5 mg/kg, respectively). In isolated working rat hearts, bimoclomol increased coronary now (CF), decreased the reduction of cardiac output (CO) and left ventricular developed pressure (LVDP) developing after coronary occlusion, and prevented ventricular fibrillation (VF) during reperfusion. In rabbit aortic preparations, precontracted with phenylephrine, bimoclomol induced relaxation (EC50=214 muM). Bimoclomol produced partial relaxation against 20 mM KCl, however, bimoclomol failed to relax preparations precontracted with serotonin, PGF(2) or angiotensin II. All these effects were evident within a few minutes after application of bimoclomol. A rapid bimoclomol-induced compartmental translocation of the already preformed HSPs may explain the protective action of the compound. (C) 2001 Elsevier Science Inc. All rights reserved.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:General Pharmacology-the Vascular System. - 34 : 5 (2000), p. 363-369. -
További szerzők:Ferdinándy Péter Jaszlits László Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Szigligeti Péter Körtvély Ágnes Szentmiklósi József András (1948-) (farmakológus, klinikai laboratóriumi szakorvos) Nánási Péter Pál (1956-) (élettanász)
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4.

001-es BibID:BIBFORM030267
Első szerző:Körtvély Ágnes
Cím:Cardiovascular effects of BRX-005 comparison to bimoclomol / Ágnes Körtvély, Gyula Szigeti, Rudolf Gesztelyi, Judit Zsuga, Tamás Bányász, János Magyar, Péter Szigligeti, László Kovács, Andrea Jednákovits, A. József Szentmiklósi, Péter P. Nánási
Dátum:2000
ISSN:0024-3205
Megjegyzések:Concentration-dependent effects of BRX-005, the novel heat shock protein coinducer, cardioprotective and vasoprotective agent, on intracellular calcium transients and contractility were studied in Langendorff-perfused guinea pig hearts loaded with the fluorescent calcium indicator dye Fura-2. BRX-005 increased peak left ventricular pressure, the rate of force development and relaxation significantly in a concentration-dependent manner. The amplitude of [Ca2+](i) transients was left unaltered by the drug, in contrast to BRX-005, bimoclomol increased both contractility and the amplitude of [Ca2+](i) transients, In canine ventricular cardiomyocytes high concentrations of BRX-005 had no effect on depolarization, whereas bimoclomol suppressed action potential upstroke markedly. In guinea pig pulmonary artery preparations precontracted with phenylephrine, BRX-005 induced concentration-dependent relaxation. This effect of BRX-005 was independent of the integrity of endothelium indicating that vasorelaxant effect of the drug develops directly on vascular smooth muscle, (C) 2000 Elsevier Science Inc. All rights reserved.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Life Sciences. - 67 : 14 (2000), p. 1783-1789. -
További szerzők:Szigeti Gyula (1969-) (élettanász, elektrofiziológus) Gesztelyi Rudolf (1969-) (kísérletes farmakológus) Zsuga Judit (1973-) (neurológus, pszichoterapeuta, egészségügyi szakmanager) Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Szigligeti Péter Kovács László (1939-) (élettanász) Jednákovits Andrea Szentmiklósi József András (1948-) (farmakológus, klinikai laboratóriumi szakorvos) Nánási Péter Pál (1956-) (élettanász)
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5.

001-es BibID:BIBFORM030270
035-os BibID:WOS:000165611500019
Első szerző:Magyar János (élettanász)
Cím:Effects of endothelin-1 on calcium and potassium currents in undiseased human ventricular myocytes / J. Magyar, N. Iost, Á. Körtvély, T. Bányász, L. Virág, P. Szigligeti, A. Varró, M. Opincariu, J. Szécsi, J. G. Papp, P. P. Nánási
Dátum:2000
ISSN:0031-6768
Megjegyzések:Endothelins have been reported to exert a wide range of electrophysiological effects in mammalian cardiac cells. These results are controversial and human data are not available. Our aim was to study the effects of endothelin-l (ET-1, 8 nmol/l) on the L-type calcium current (ICa-L) and various potassium currents (rapid component of the delayed rectifier, I-Kr; transient outward current, I-to; and the inward rectifier K current, I-K1) in isolated human ventricular cardiomyocytes. Cells were obtained from undiseased donor hearts using collagenase digestion via the segment perfusion technique. The whole-cell configuration of the patch-clamp technique was applied to measure ionic currents at 37 degreesC. ET-1 significantly decreased peak I-Ca,I-L from 10.2+/-0.6 to 6.8+/-0.8 pA/pF at +5 mV (66.7% of control, P <0.05, n=5). This reduction of peak current was accompanied by a lengthening of inactivation. The voltage dependence of steady-state activation and inactivation was not altered by ET-1. I-Kr, measured as tail current amplitudes at -40 mV, decreased from 0.31+/-0.02 to 0.06+/-0.02 pA/pF (20.3% of control, P <0.05, n=4) after exposure to ET-1. ET-I failed to change the peak amplitude of I-to, measured at +50 mV (9.3+/-4.6 and 9.0+/-4.4 pA/pF before and after ET-1, respectively), or steady-state I-K1 amplitude, measured at the end of a 400-ms hyperpolarization to -100 mV (3.6+/-1.4 and 3.7+/-1.4 pA/pF, n=4). The present results indicate that in undiseased human ventricular myocytes ET-1 inhibits both ICa-L and I-Kr; however, the degree of suppression of the two currents is different.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Pflügers Archiv. - 441 : 1 (2000), p. 144-149. -
További szerzők:Iost, N. Körtvély Ágnes Bányász Tamás (1960-) (élettanász) Virág László (élettanász Szeged) Szigligeti Péter Varró András (1954-) (farmakológus, klinikai farmakológus) Opincariu, M. Szécsi János (1955-) (szívsebész) Papp Gy. Julius (Szeged) Nánási Péter Pál (1956-) (élettanász)
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6.

001-es BibID:BIBFORM030265
035-os BibID:WOS:000085470500011
Első szerző:Magyar János (élettanász)
Cím:Electrophysiological effects of bimoclomol in canine ventricular myocytes / János Magyar, Tamás Bányász, Péter Szigligeti, Ágnes Körtvély, Andrea Jednákovits, Péter P. Nánási
Dátum:2000
ISSN:0028-1298
Megjegyzések:Concentration-dependent effects of bimoclomol, a novel heat shack protein (HSP) coinducer, were studied on the parameters of action potential and transmembrane ionic currents in enzymatically dispersed canine ventricular cardiomyocytes using conventional microelectrode and whole cell voltage clamp techniques. Bimoclomol (10-100 mu M) decreased the maximum velocity of depolarization ((V) over dot(max)) and amplitude of action potentials in a concentration-dependent manner. These effects were fully reversible after a 5-min period of washout in drug-free medium. Action potential duration measured at 50% or 90% level of repolarization (APD-50 and APD-90, respectively) was markedly shortened by bimoclomol. Both APD-50 and APD-90 were decreased, but the reduction in APD-50 was more pronounced. The APD-shortening effect of bimoclomol was significantly reduced in the presence of 20 nM charybdotoxin (inhibitor of the Ca-dependent K current) or 0.5 mM anthracene-9-carboxylic acid (inhibitor of the Ca-dependent Cl current) or 1 mu M glibenclamide (inhibitor of the ATP-sensitive K current). In the presence of anthracene-9-carboxylic acid, APD-90 was lengthened by bimoclomol. The APD-shortening effect of bimoclomol was also partially antagonized by chelation of intracellular Ca2+ by application of the cell permeant form of BAPTA, or when using 10 mM EGTA-containing patch pipettes to record action potentials. The (V) over dot(max)-depressant effect of bimoclomol was not affected by charybdotoxin, anthracene-9-carboxylic acid, glibenclamide, or BAPTA load. In voltage clamped cardiomyocytes bimoclomol (100 mu M) had no effect all the amplitude of I-Ca, but decreased significantly the inactivation time constant of I-Ca (from 19.8+/-1.6 ms to 16.8+/-1.2 ms at 0 mV). Bimoclomol also decreased significantly the amplitude of I-K1 (from -20.5+/-1.1 pA/pF to -16.6+/-0.8 pA/pF at -135 mV), causing reduction in slope of the negative branch of the I-V curve. At positive potentials, however, bimoclomol increased outward current. The bimoclomol-induced current, therefore, was studied in the presence of BaCl2, when I-K1 current was blocked. The bimoclomol-induced current had a reversal potential close to -90 mV. Bimoclomol (100 mu M) had no effect on the amplitude or kinetic properties of the transient outward K current (I-to) and the delayed rectifier K current (I-K). It is concluded that bimoclomol exerts both Ca-independent (inhibition of I-Na and I-K1, activation of the ATP-sensitive K current) and Ca-dependent effects (mediated by Ca-activated Cl and probably K currents) in canine ventricular myocytes.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Naunyn-Schmiedebergs Archives of Pharmacology. - 361 : 3 (2000), p. 303-310. -
További szerzők:Bányász Tamás (1960-) (élettanász) Szigligeti Péter Körtvély Ágnes Jednákovits Andrea Nánási Péter Pál (1956-) (élettanász)
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7.

001-es BibID:BIBFORM030339
035-os BibID:PMID: 8899061 WOS:A1996VL12100005
Első szerző:Nánási Péter Pál (élettanász)
Cím:Electrical restitution in rat ventricular muscle / P. P. Nanasi, Cs. Pankucsi, T. Banyasz, P. Szigligeti, J. Gy. Papp, A. Varro
Dátum:1996
ISSN:0001-6772
Megjegyzések:The mechanism of electrical restitution was studied in isolated rat ventricular muscle using drugs that inhibit specific ion currents. The effect of transient changes in cytosolic Ca concentration and Na/Ca exchange in relation to the restitution process was also studied in single ventricular cardiomyocytes. Conventional microelectrode techniques were applied to record action potentials having gradually increasing coupling intervals. each evoked following a train of stimuli with a frequency of 1 Hz. ion currents were recorded from enzymatically isolated cells using the whole cell parch clamp technique. Ca transients were monitored in myocytes loaded with the fluorescent dye, indo-1. The electrical restitution process in multicellular rat ventricular preparations at 37 degrees C was described as a sum oi three exponential components: an early positive component. a subsequent fast negative component and a late negative component. having time constants of 21.9 +/- 1.9, 73.1 +/- 6.0 and 1053 +/- 61 ms, respectively (n = 9). Inhibition of the transient outward K current the delayed rectifier K current. or the chloride current did not substantially alter these time constants, The early positive and fast negative components were fully abolished by nifedipine or MnCl2. In the presence of caffeine. the fast negative component was absent. while the time constant of the early positive component increased to 39.5 +/- 5.8 ms (n = 5). In single myocytes loaded with indo-1, the Ca transients decayed with a time constant of 151 +/- 12 ms at room temperature (n = 5). These Ca transients were accompanied by inward current tails. identified as a Na/Ca exchange current. having a decay time constant of 140 +/- 4.5 ms. It is concluded that electrical restitution in rat ventricular muscle is relatively little affected by recovery from voltage-dependent inactivation of ion channels. it is rather governed by transient changes in cytosolic Ca concentration possible via Ca-dependent inactivation of the L-type Ca current and activation of the Na/Ca exchange current.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Acta Physiologica Scandinavica. - 158 : 2 (1996), p. 143-153. -
További szerzők:Pankucsi Csaba (farmakológus) Bányász Tamás (1960-) (élettanász) Szigligeti Péter Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus)
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8.

001-es BibID:BIBFORM030264
035-os BibID:WOS:000086138300017
Első szerző:Nánási Péter Pál (élettanász)
Cím:Biphasic effect of bimoclomol on calcium handling in mammalian ventricular myocardium / Péter P. Nánási, Sándor Sárközi, Gyula Szigeti, István Jóna, Csaba Szegedi, Ágnes Szabó, Tamás Bányász, János Magyar, Péter Szigligeti, Ágnes Körtvély, László Csernoch, László Kovács, Andrea Jednákovits
Dátum:2000
ISSN:0007-1188
Megjegyzések:1 Concentration-dependent effects of bimoclomol, the novel heat shock protein coinducer, on intracellular calcium transients and contractility were studied in Langendorff-perfused guinea-pig hearts loaded with the fluorescent calcium indicator dye Fura-2. Bimoclomol had a biphasic effect on contractility: both peak left ventricular pressure and the rate of force development significantly increased at a concentration of 10 nM or higher. The maximal effect was observed between 0.1 and 1 mu M, and the positive inotropic action disappeared by further increasing the concentration of bimoclomol. The drug increased systolic calcium concentration with a similar concentration-dependence. In contrast, diastolic calcium concentration increased monotonically in the presence of bimoclomol. Thus low concentrations of the drug (10-100 nM) increased, whereas high concentrations (10 mu M) decreased the amplitude of intracellular calcium transients. 2 Effects of bimoclomol on action potential configuration was studied in isolated canine ventricular myocytes. Action potential duration was increased at low (10 nM), unaffected at intermediate (0.1-1 mu M) and decreased at high (10-100 mu M) concentrations of the drug. 3 In single canine sarcoplasmic calcium release channels (ryanodine receptor), incorporated into artificial lipid bilayer, bimoclomol significantly increased the open probability of the channel in the concentration range of 1-10 mu M. The increased open probability was associated with increased mean open time. The effect of bimoclomol was again biphasic: the open probability decreased below the control level in the presence of 1 mM bimoclomol. 4 Bimoclomol (10 mu M-1 mM) had no significant effect on the rate of calcium uptake into sarcoplasmic reticulum vesicles of the dog, indicating that in vivo calcium reuptake might not substantially be affected by the drug. 5 In conclusion, the positive inotropic action of bimoclomol is likely due to the activation of the sarcoplasmic reticulum calcium release channel in mammalian ventricular myocardium.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:British Journal of Pharmacology. - 129 : 7 (2000), p. 1405-1412. -
További szerzők:Sárközi Sándor (1966-) (élettanász) Szigeti Gyula (1969-) (élettanász, elektrofiziológus) Jóna István (1948-) (élettanász, fizikus) Szegedi Csaba Szabó Ágnes Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Szigligeti Péter Körtvély Ágnes Csernoch László (1961-) (élettanász) Kovács László (1939-) (élettanász) Jednákovits Andrea
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9.

001-es BibID:BIBFORM030266
035-os BibID:WOS:000084701100010
Első szerző:Pacher Pál
Cím:Electrophysiological effects of fluoxetine in mammalian cardiac tissues / Pál Pacher, János Magyar, Péter Szigligeti, Tamás Bányász, Csaba Pankucsi, Zsuzsanna Korom, Zoltán Ungvári, Valéria Kecskeméti, Péter P. Nánási
Dátum:2000
ISSN:0028-1298
Megjegyzések:Fluoxetine is a widely used antidepressant compound having selective serotonin reuptake inhibitor properties. In this study, the actions of fluoxetine were analyzed in guinea pig, rat, rabbit and canine ventricular myocardiac preparations using conventional microelectrode and whole cell voltage clamp techniques. Low concentrations of fluoxetine (1-10 mu mol/l) caused significant shortening of action potential duration (APD) and depression of the plateau potential in guinea pig and rabbit papillary muscles and single canine ventricular myocytes. In rat papillary muscle, APD was not affected by fluoxetine (up to 100 mu mol/l), however, the drug decreased the force of contraction with EC50 of 10 mu mol/l. Fluoxetine (10 mu mol/l) also decreased the maximum velocity of depolarization and action potential overshoot in each species studied. At this concentration no effect was observed on the resting membrane potential; high concentration (100 mu mol/l), however, caused depolarization. In voltage clamped canine ventricular myocytes, fluoxetine caused concentration-dependent block of the peak Ca2+ current at 0 mV with EC50 Of 5.4+/-0.94 mu mol/l and Hill coefficient of 1.1+/-0.14 (n=6). In addition, 10 mu mol/l fluoxetine shifted the midpoint of the steady-state inactivation curve of the Ca2+ current from -20.7+/-0.65 to -26.7+/-1 mV (P<0.001, n=8) without changing its slope factor. These effects of fluoxetine developed rapidly and were fully reversible. Fluoxetine did not alter voltage-dependence of activation or time constant for inactivation of I-Ca. Fluoxetine had no effect on the amplitude of K+ currents (I-K1 and I-to). The inhibition of cardiac Ca2+ and Na+ channels by fluoxetine may explain most cardiac side effects observed occasionally with the drug. Our results suggest that fluoxetine may have antiarrhythmic (class I + IV type), as well as proarrhythmic properties (due to impairment of atrioventricular or intraventricular conduction and shortening of repolarization). Therefore, in depressed patients with cardiac disorders, ECG control may be suggested during fluoxetine therapy.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Naunyn-Schmiedebergs Archives of Pharmacology. - 361 : 1 (2000), p. 67-73. -
További szerzők:Magyar János (1961-) (élettanász) Szigligeti Péter Bányász Tamás (1960-) (élettanász) Pankucsi Csaba (farmakológus) Korom Zsuzsanna Ungvári Zoltán Kecskeméti Valéria Nánási Péter Pál (1956-) (élettanász)
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10.

001-es BibID:BIBFORM030269
Első szerző:Szigeti Gyula (élettanász, elektrofiziológus)
Cím:Effects of bimoclomol, the novel heat shock protein coinducer, in dog ventricular myocardium / Gyula Szigeti, Tamás Bányász, János Magyar, Ágnes Körtvély, Péter Szigligeti, László Kovács, Andrea Jednákovits, Péter P. Nánási
Dátum:2000
ISSN:0024-3205
Megjegyzések:The effects of the novel HSP-coinducer bimoclomol was studied on action potentials, ionic currents and [Ca2+](i) transients in isolated canine ventricular myocytes using conventional microelectrode techniques and whole cell voltage clamp combined with fluorescent [Ca2+](i) measurements. Contractility was studied in right ventricular trabeculae, All preparations were paced with a frequency of 0.2 Hz. Bimoclomol (100 mu M) shortened action potential duration measured at 50% repolarization, but lengthened action potentials at the 90% repolarization level, decreased action potential amplitude and maximum depolarization velocity in a reversible manner. In voltage clamped myocytes, the drug activated a steady-state outward current at positive membrane potentials leaving the peak inward current unaffected, [Ca2+](i) transients, measured under voltage clamp control, were increased in amplitude and had accelerated decay kinetics in the presence of the compound, in addition to reduction of diastolic [Ca2+](i). Bimoclomol significantly decreased the force of contraction in right ventricular trabeculae. Comparison of present data to previous results indicate that the cardiac effects of bimoclomol strongly depend on actual experimental conditions. The reduced contractility in spite of the increased amplitude of [Ca2+](i) transients suggests that 100 mu M bimoclomol may decrease calcium sensitivity of the contractile apparatus. (C) 2000 Elsevier Science Inc. All rights reserved.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Life Sciences. - 67 : 1 (2000), p. 73-79. -
További szerzők:Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Körtvély Ágnes Szigligeti Péter Kovács László (1939-) (élettanász) Jednákovits Andrea Nánási Péter Pál (1956-) (élettanász)
Internet cím:DOI
elektronikus változat
Intézményi repozitóriumban (DEA) tárolt változat
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11.

001-es BibID:BIBFORM030337
035-os BibID:PMID: 8766913 WOS:A1996UW72900009
Első szerző:Szigligeti Péter
Cím:Action potential duration and force-frequency relationship in isolated rabbit, guinea pig and rat cardiac muscle / P. Szigligeti, Cs. Pankucsi, T. Banyasz, A. Varro, P. P. Nanasi
Dátum:1996
ISSN:0174-1578
Megjegyzések:The effect of action potential duration and elevated cytosolic sodium concentration on the force-frequency relationship in isolated rabbit, guinea pig and rat papillary muscle preparations was studied. Shortening of action potential duration in guinea pig and rabbit from 150-200 ms to values characteristic of rat (20-40 ms), using the K-(ATP) channel activator levkromakalim (15 mu mol . l(-1)), markedly reduced the force of contraction and converted the positive force-frequency relationship into negative one at longer pacing cycle lengths. This conversion was greatly enhanced in the presence of acetylstrophanthidin (0.2-1 mu mol . l(-1)), an inhibitor of the Na-K pump. Acetylstrophanthidin (1 mu mol . l(-1)) alone, however, had no effect on the force-frequency relationship. Prolongation of action potential duration in rat with inhibitors of cardiac K channels (4-aminopyridine [10 mmol . l(-1)] plus tetraethylammonium [2 mmol . l(-1)] increased the force of contraction and abolished the negative force-frequency relationship observed in rat at longer pacing-cycle lengths. It is concluded that both action potential duration and cytosolic sodium concentration are major determinants of the force-frequency relationship in mammalian myocardium.
Tárgyszavak:Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
egyetemen (Magyarországon) készült közlemény
Megjelenés:Journal of Comparative Physiology B-Biochemical Systemic and Environmental Physiology. - 166 : 2 (1996), p. 150-155. -
További szerzők:Pankucsi Csaba (farmakológus) Bányász Tamás (1960-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
Internet cím:DOI
Intézményi repozitóriumban (DEA) tárolt változat
Borító:

12.

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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