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001-es BibID:	BIBFORM016600
Első szerző:	Bárándi László (élettanász)
Cím:	Reverse rate-dependent changes are determined by baseline action potential duration in mammalian and human ventricular preparations / Bárándi László, Virág László, Jost Norbert, Horváth Zoltán, Koncz István, Papp Rita, Harmati Gábor, Horváth Balázs, Szentandrássy Norbert, Bányász Tamás, Magyar János, Zaza Antonio, Varró András, Nánási Péter P.
Dátum:	2010
ISSN:	0300-8428
Megjegyzések:	Class III antiarrhythmic agents exhibit reverse rate-dependent lengthening of the action potential duration (APD). In spite of the several theories developed so far to explain this reverse rate-dependency (RRD), its mechanism has not yet been clarified. The aim of the present work was to further elucidate the mechanisms responsible for RRD in mammalian ventricular myocardium. Action potentials were recorded using conventional sharp microelectrodes from human, canine, rabbit and guinea pig ventricular myocardium in a rate-dependent manner varying the cycle length (CL) between 0.3 and 5 s. Rate-dependent drug effects were studied using agents known to lengthen or shorten action potentials, and these drug-induced changes in APD were correlated with baseline APD values. Both drug-induced lengthening (by dofetilide, sotalol, E-4031, BaCl2, veratrine, BAY K 8644) and shortening (by mexiletine, tetrodotoxin, lemakalim) of action potentials displayed RRD, i.e., changes in APD were greater at longer than at shorter CLs. In rabbit, where APD is a biphasic function of CL, the drug-induced APD changes were proportional to baseline APD values but not to CL. Similar results were obtained when repolarization was modified by injection of inward or outward current pulses in isolated canine cardiomyocytes. In each case the change in APD was proportional to baseline APD (i.e., that measured before the superfusion of drug or injection of current). Also, the net membrane current (Inet), determined from the action potential waveform at the middle of the plateau, was inversely proportional to APD and consequently with to CL. The results indicate that RRD is a common characteristic of all the drugs tested regardless of the modified ion current species. Thus, drug-induced RRD can be considered as an intrinsic property of cardiac membranes based on the inverse relationship between Inet and APD.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Ventricular repolarization Action potential duration Reverse rate dependence Membrane current Human myocardium Mammalian cardiac cells egyetemen (Magyarországon) készült közlemény
Megjelenés:	Basic Research In Cardiology. - 105 : 3 (2010), p. 315-323. -
További szerzők:	Virág László (élettanász Szeged) Jost Norbert Horváth Zoltán Koncz István (Szeged) Papp Rita Harmati Gábor (1983-) (élettanász) Horváth Balázs (1981-) (élettanász) Szentandrássy Norbert (1976-) (élettanász) Bányász Tamás (1960-) (élettanász) Magyar János (1961-) (élettanász) Zaza, Antonio Varró András (1954-) (farmakológus, klinikai farmakológus) Nánási Péter Pál (1956-) (élettanász)
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001-es BibID:	BIBFORM009061
Első szerző:	Jost Norbert
Cím:	Contribution of I Kr and I K1 to ventricular repolarization in canine and human myocytes : is there any influence of action potential duration? / Jost, N., Acsai, K., Horvath, B., Banyasz, T., Baczko, I., Bitay, M., Bogats, G., Nanasi, P. P.
Dátum:	2009
ISSN:	0300-8428 (Print)
Megjegyzések:	The aim of the present work was to study the profile of the rapid delayed rectifier potassium current (I (Kr)) and the inward rectifier potassium current (I (K1)) during ventricular repolarization as a function of action potential duration and rate of repolarization. METHODS: Whole cell configuration of the patch clamp technique was used to monitor I (Kr) and I (K1) during the action potential plateau and terminal repolarization. Action potentials recorded at various cycle lengths (0.4-5 s) and repolarizing voltage ramps having various slopes (0.5-3 V/s) were used as command signals. I (Kr) and I (K1) were identified as difference currents dissected by E-4031 and BaCl(2), respectively. RESULTS: Neither peak amplitudes nor mean values of I (Kr) and I (K1) recorded during the plateau of canine action potentials were influenced by action potential duration. The membrane potential where I (Kr) and I (K1) peaked during the terminal repolarization was also independent of action potential duration. Similar results were obtained in undiseased human ventricular myocytes, and also in canine cells when I (Kr) and I (K1) were evoked using repolarizing voltage ramps of various slopes. Action potential voltage clamp experiments revealed that the peak values of I (Kr), I (K1), and net outward current during the terminal repolarization were independent of the pacing cycle length within the range of 0.4 and 5 s. CONCLUSIONS: The results indicate that action potential configuration fails to influence the amplitude of I (Kr) and I (K1) during the ventricular action potential in dogs and humans, suggesting that rate-dependent changes in action potential duration are not likely related to rate-dependent alterations in I (Kr) or I (K1) kinetics in these species.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Action Potentials Animals Barium Compounds Chlorides Dogs Electrophysiology Humans KATP Channels Kinetics Muscle Cells Patch-Clamp Techniques Potassium Channels, Inwardly Rectifying Reference Values Ventricular Function
Megjelenés:	Basic Research in Cardiology. - 104 : 1 (2009), p. 33-41. -
További szerzők:	Acsai Károly Horváth Balázs (1981-) (élettanász) Bányász Tamás (1960-) (élettanász) Baczkó István Bitay Miklós Bogáts Gábor Nánási Péter Pál (1956-) (élettanász)
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001-es BibID:	BIBFORM030348
035-os BibID:	PMID:8389123 WOS:A1993LB18500001
Első szerző:	Varró András (farmakológus, klinikai farmakológus)
Cím:	Ionic currents and action potentials in rabbit, rat, and guinea pig ventricular myocytes / A. Varro, D. A. Lathrop, S. B. Hester, P. P. Nanasi, J. Gy. Papp
Dátum:	1993
ISSN:	0300-8428
Megjegyzések:	Distinct differences exist in action potentials and ionic currents between rabbit, rat, and guinea pig ventricular myocytes. Data obtained at room temperature indicate that about half of the rabbit myocytes show prominent phase 1 repolarization and transient outward current. Action potentials in guinea pig ventricular myocytes resemble those from rabbit myocytes not exhibiting phase 1 repolarization; and guinea pig myocytes do not develop transient outward current. Rat ventricular action potentials are significantly shorter than those from rabbit and guinea pig ventricular myocytes. Unlike rabbit and guinea pig myocytes, rat ventricular myocytes also exhibit a prominent phase 1 and lack a well defined plateau phase during repolarization. All rat ventricular myocytes exhibit a transient outward current which can be best fitted by a double exponential relation. There are no significant differences between the amplitude, voltage dependence and inactivation kinetics of the inward calcium currents observed in rabbit, rat and guinea pig. The steady-state current-voltage relations between -120 mV and -20 mV, which mostly represent the inward rectifier potassium current are similar in rabbit and guinea pig. The amplitude of this current is significantly less in rat ventricular myocytes. The outward currents activated upon depolarization to between -10 and +50 mV are different in the three species. Only a negligible, or absent, delayed rectifier outward current has been observed in rabbit and rat; however, a relatively large delayed rectifier current has been found in guinea pig. These large interspecies variations in outward membrane currents help explain the differences in action potential configurations observed in rabbit, rat, and guinea pig.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban egyetemen (Magyarországon) készült közlemény
Megjelenés:	Basic Research in Cardiology. - 88 : 2 (1993), p. 93-102. -
További szerzők:	Lathrop, David A. Hester, S. B. Nánási Péter Pál (1956-) (élettanász) Papp Gy. Julius (Szeged)
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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