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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.
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.
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
Barium Compounds
KATP Channels
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)
Internet cím:DOI
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