@article{MTMT:33364863,
	title = {The reverse mode of the Na+/Ca2+ exchanger contributes to the pacemaker mechanism in rabbit sinus node cells},
	url = {https://m2.mtmt.hu/api/publication/33364863},
	author = {Tóth, Noémi and Loewe, Axel and Szlovák, Jozefina and Kohajda, Zsófia and Bitay, Gergő and Levijoki, Jouko and Papp, Gyula and Varró, András and Nagy, Norbert},
	doi = {10.1038/s41598-022-25574-8},
	journal-iso = {SCI REP},
	journal = {SCIENTIFIC REPORTS},
	volume = {12},
	unique-id = {33364863},
	issn = {2045-2322},
	abstract = {Sinus node (SN) pacemaking is based on a coupling between surface membrane ion-channels and intracellular Ca 2+ -handling. The fundamental role of the inward Na + /Ca 2+ exchanger (NCX) is firmly established. However, little is known about the reverse mode exchange. A simulation study attributed important role to reverse NCX activity, however experimental evidence is still missing. Whole-cell and perforated patch-clamp experiments were performed on rabbit SN cells supplemented with fluorescent Ca 2+ -tracking. We established 2 and 8 mM pipette NaCl groups to suppress and enable reverse NCX. NCX was assessed by specific block with 1 μM ORM-10962. Mechanistic simulations were performed by Maltsev–Lakatta minimal computational SN model. Active reverse NCX resulted in larger Ca 2+ -transient amplitude with larger SR Ca 2+ -content. Spontaneous action potential (AP) frequency increased with 8 mM NaCl. When reverse NCX was facilitated by 1 μM strophantin the Ca 2+ i and spontaneous rate increased. ORM-10962 applied prior to strophantin prevented Ca 2+ i and AP cycle change. Computational simulations indicated gradually increasing reverse NCX current, Ca 2+ i and heart rate with increasing Na + i . Our results provide further evidence for the role of reverse NCX in SN pacemaking. The reverse NCX activity may provide additional Ca 2+ -influx that could increase SR Ca 2+ -content, which consequently leads to enhanced pacemaking activity.},
	year = {2022},
	eissn = {2045-2322},
	orcid-numbers = {Varró, András/0000-0003-0745-3603}
}

@article{MTMT:32670331,
	title = {Long-Term Endurance Exercise Training Alters Repolarization in a New Rabbit Athlete’s Heart Model},
	url = {https://m2.mtmt.hu/api/publication/32670331},
	author = {Kui, Péter and Polyák, Alexandra Júlia and Morvay, Nikolett and Tiszlavicz, László and Nagy, Norbert and Ördög, Balázs and Takács, Hedvig and Leprán, István and Farkas, András and Papp, Gyula and Jost, Norbert László and Varró, András and Baczkó, István and Farkas, Attila},
	doi = {10.3389/fphys.2021.741317},
	journal-iso = {FRONT PHYSIOL},
	journal = {FRONTIERS IN PHYSIOLOGY},
	volume = {12},
	unique-id = {32670331},
	year = {2022},
	eissn = {1664-042X},
	orcid-numbers = {Tiszlavicz, László/0000-0003-1134-6587; Ördög, Balázs/0000-0002-8971-3079; Varró, András/0000-0003-0745-3603; Baczkó, István/0000-0002-9588-0797}
}

@article{MTMT:32462674,
	title = {Aritmogén kamrai alternánsok celluláris mechanizmusának vizsgálata szívizomban = The role of membrane potential and restitution in the mechanism of cardiac alternans},
	url = {https://m2.mtmt.hu/api/publication/32462674},
	author = {Tóth, Noémi and Kohajda, Zsófia and Szlovák, Jozefina and Bitay, Gergő and Veress, R and Horváth, Balázs and Papp, Gyula and Varró, András and Nagy, Norbert},
	journal-iso = {CARDIOL HUNG},
	journal = {CARDIOLOGIA HUNGARICA},
	volume = {51},
	unique-id = {32462674},
	issn = {0133-5596},
	year = {2021},
	eissn = {1588-0230},
	pages = {B253-B254},
	orcid-numbers = {Horváth, Balázs/0000-0003-2562-8446; Varró, András/0000-0003-0745-3603}
}

@article{MTMT:32246276,
	title = {The role of action potential restitution versus Ca2+ cycling in the mechanism of alternans in canine ventricular myocardium},
	url = {https://m2.mtmt.hu/api/publication/32246276},
	author = {Nagy, Norbert and Tóth, Noémi and Kohajda, Zsófia and Szlovák, Jozefina and Bitay, Gergő and Veress, Roland and Horváth, Balázs and Papp, Gyula and Varró, András},
	journal-iso = {SCRIPTA MEDICA},
	journal = {SCRIPTA MEDICA},
	volume = {52},
	unique-id = {32246276},
	issn = {1211-3395},
	year = {2021},
	pages = {S72},
	orcid-numbers = {Horváth, Balázs/0000-0003-2562-8446; Varró, András/0000-0003-0745-3603}
}

@article{MTMT:32246069,
	title = {Investigation of the reverse Na+/Ca2+ exchanger function in the spontaneous automaticity of rabbit sinus node cells},
	url = {https://m2.mtmt.hu/api/publication/32246069},
	author = {Tóth, Noémi and Loewe, A and Kohajda, Zsófia and Bitay, Gergő and Levijoki, J and Papp, Gyula and Varró, András and Nagy, Norbert},
	journal-iso = {SCRIPTA MEDICA},
	journal = {SCRIPTA MEDICA},
	volume = {52},
	unique-id = {32246069},
	issn = {1211-3395},
	year = {2021},
	pages = {S16},
	orcid-numbers = {Varró, András/0000-0003-0745-3603}
}

@article{MTMT:32153454,
	title = {The development of L-type Ca2+ current mediated alternans does not depend on the restitution slope in canine ventricular myocardium},
	url = {https://m2.mtmt.hu/api/publication/32153454},
	author = {Tóth, Noémi and Szlovák, Jozefina and Kohajda, Zsófia and Bitay, Gergő and Veress, Roland and Horváth, Balázs and Papp, Gyula and Varró, András and Nagy, Norbert},
	doi = {10.1038/s41598-021-95299-7},
	journal-iso = {SCI REP},
	journal = {SCIENTIFIC REPORTS},
	volume = {11},
	unique-id = {32153454},
	issn = {2045-2322},
	abstract = {Cardiac alternans have crucial importance in the onset of ventricular fibrillation. The early explanation for alternans development was the voltage-driven mechanism, where the action potential (AP) restitution steepness was considered as crucial determining factor. Recent results suggest that restitution slope is an inadequate predictor for alternans development, but several studies still claim the role of membrane potential as underlying mechanism of alternans. These controversial data indicate that the relationship of restitution and alternans development is not completely understood. APs were measured by conventional microelectrode technique from canine right ventricular papillary muscles. Ionic currents combined with fluorescent measurements were recorded by patch-clamp technique. APs combined with fluorescent measurements were monitored by sharp microelectrodes. Rapid pacing evoked restitution-independent AP duration (APD) alternans. When non-alternating AP voltage command was used, Ca2+i-transient (CaT) alternans were not observed. When alternating rectangular voltage pulses were applied, CaT alternans were proportional to ICaL amplitude alternans. Selective ICaL inhibition did not influence the fast phase of APD restitution. In this study we found that ICaL has minor contribution in shaping the fast phase of restitution curve suggesting that ICaL—if it plays important role in the alternans mechanism—could be an additional factor that attenuates the reliability of APD restitution slope to predict alternans.},
	year = {2021},
	eissn = {2045-2322},
	orcid-numbers = {Horváth, Balázs/0000-0003-2562-8446; Varró, András/0000-0003-0745-3603}
}

@article{MTMT:32073842,
	title = {Author Correction: Increased Ca2+ content of the sarcoplasmic reticulum provides arrhythmogenic trigger source in swimming-induced rat athlete’s heart model},
	url = {https://m2.mtmt.hu/api/publication/32073842},
	author = {Gazdag, Péter and Oravecz, Kinga and Acsai, Károly and Demeter-Haludka, Vivien and Ördög, Balázs and Szlovák, Jozefina and Kohajda, Zsófia and Polyák, Alexandra Júlia and Barta, Bálint András and Oláh, Attila and Radovits, Tamás and Merkely, Béla Péter and Papp, Gyula and Baczkó, István and Varró, András and Nagy, Norbert and Prorok, János},
	doi = {10.1038/s41598-021-91695-1},
	journal-iso = {SCI REP},
	journal = {SCIENTIFIC REPORTS},
	volume = {11},
	unique-id = {32073842},
	issn = {2045-2322},
	abstract = {An amendment to this paper has been published and can be accessed via a link at the top of the paper. © 2021, The Author(s).},
	keywords = {erratum},
	year = {2021},
	eissn = {2045-2322},
	orcid-numbers = {Ördög, Balázs/0000-0002-8971-3079; Merkely, Béla Péter/0000-0001-6514-0723; Baczkó, István/0000-0002-9588-0797; Varró, András/0000-0003-0745-3603; Prorok, János/0000-0001-8419-8859}
}

@article{MTMT:31795546,
	title = {Blockade of sodium‑calcium exchanger via ORM-10962 attenuates cardiac alternans},
	url = {https://m2.mtmt.hu/api/publication/31795546},
	author = {Szlovák, Jozefina and Tomek, Jakub and Zhou, Xin and Tóth, Noémi and Veress, Roland and Horváth, Balázs and Szentandrássy, Norbert and Levijoki, Jouko and Papp, Gyula and Herring, Neil and Varró, András and Eisner, David A and Rodriguez, Blanca and Nagy, Norbert},
	doi = {10.1016/j.yjmcc.2020.12.015},
	journal-iso = {J MOL CELL CARDIOL},
	journal = {JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY},
	volume = {153},
	unique-id = {31795546},
	issn = {0022-2828},
	abstract = {Repolarization alternans, a periodic oscillation of long-short action potential duration, is an important source of arrhythmogenic substrate, although the mechanisms driving it are insufficiently understood. Despite its relevance as an arrhythmia precursor, there are no successful therapies able to target it specifically. We hypothesized that blockade of the sodium‑calcium exchanger (NCX) could inhibit alternans. The effects of the selective NCX blocker ORM-10962 were evaluated on action potentials measured with microelectrodes from canine papillary muscle preparations, and calcium transients measured using Fluo4-AM from isolated ventricular myocytes paced to evoke alternans. Computer simulations were used to obtain insight into the drug's mechanisms of action. ORM-10962 attenuated cardiac alternans, both in action potential duration and calcium transient amplitude. Three morphological types of alternans were observed, with differential response to ORM-10962 with regards to APD alternans attenuation. Analysis of APD restitution indicates that calcium oscillations underlie alternans formation. Furthermore, ORM-10962 did not markedly alter APD restitution, but increased post-repolarization refractoriness, which may be mediated by indirectly reduced L-type calcium current. Computer simulations reproduced alternans attenuation via ORM-10962, suggesting that it is acts by reducing sarcoplasmic reticulum release refractoriness. This results from the ORM-10962-induced sodium‑calcium exchanger block accompanied by an indirect reduction in L-type calcium current. Using a computer model of a heart failure cell, we furthermore demonstrate that the anti-alternans effect holds also for this disease, in which the risk of alternans is elevated. Targeting NCX may therefore be a useful anti-arrhythmic strategy to specifically prevent calcium driven alternans.},
	keywords = {SODIUM-CALCIUM EXCHANGER; Canine myocytes; alternans; Cardiac simulation; Sodium‑calcium exchanger inhibition},
	year = {2021},
	eissn = {1095-8584},
	pages = {111-122},
	orcid-numbers = {Horváth, Balázs/0000-0003-2562-8446; Szentandrássy, Norbert/0000-0003-0197-9567; Varró, András/0000-0003-0745-3603}
}

@article{MTMT:31709067,
	title = {Muscarinic agonists inhibit the ATP-dependent potassium current and suppress the ventricle-Purkinje action potential dispersion},
	url = {https://m2.mtmt.hu/api/publication/31709067},
	author = {Magyar, Tibor and Árpádffy-Lovas, Tamás and Pászti, Bence József and Tóth, Noémi and Szlovák, Jozefina and Gazdag, Péter and Kohajda, Zsófia and Gyökeres, András and Györe, Balázs and Gurabi, Zsolt and Jost, Norbert László and Virág, László and Papp, Gyula and Nagy, Norbert and Koncz, Istvan},
	doi = {10.1139/cjpp-2020-0408},
	journal-iso = {CAN J PHYSIOL PHARM},
	journal = {CANADIAN JOURNAL OF PHYSIOLOGY AND PHARMACOLOGY},
	volume = {99},
	unique-id = {31709067},
	issn = {0008-4212},
	abstract = {Activation of the parasympathetic nervous system has been reported to have an antiarrhythmic role during ischemia-reperfusion injury by decreasing the arrhythmia triggers. Furthermore, it was reported that the parasympathetic neurotransmitter acetylcholine is able to modulate the ATP-dependent K-current (IK-ATP), a crucial current activated during hypoxia. However, the possible significance of this current modulation in the antiarrhythmic mechanism is not fully clarified.Action potentials were measured using the conventional microelectrode technique from canine left ventricular papillary muscle and free-running Purkinje fibers, under normal and hypoxic conditions. Ionic currents were measured using the whole-cell configuration of the patch clamp method.5 μM acetylcholine did not influence the action potential duration (APD) either in Purkinje fibers or in papillary muscle preparations. In contrast, it significantly lengthened the APD and suppressed the Purkinje-ventricle APD dispersion when it was administered after 5 μM pinacidil application. 3 μM carbachol reduced the pinacidil-activated IK-ATP under voltage-clamp condition. Acetylcholine lengthened the ventricular action potential under simulated ischemia condition.In this study we found that acetylcholine inhibits the IK-ATP and thus suppresses the ventricle-Purkinje APD dispersion. We conclude that parasympathetic tone may reduce the arrhythmogenic substrate exerting a complex antiarrhythmic mechanism during hypoxic conditions.},
	year = {2021},
	eissn = {1205-7541},
	pages = {247-253}
}

@article{MTMT:31975178,
	title = {A­ Na+/Ca 2+ ­cseremechanizmus­ szerepének­ vizsgálata­ a­ Ca 2+ ­vezérelt­ alternánsokban = The­ role­ of­ Na+/Ca 2+ ­exchanger­ in­ the­ Ca 2+ -­governed­ alternans},
	url = {https://m2.mtmt.hu/api/publication/31975178},
	author = {Szlovák, Jozefina and Tóth, Noémi and Gazdag, Péter and Papp, Gyula and Varró, András and Nagy, Norbert},
	journal-iso = {CARDIOL HUNG},
	journal = {CARDIOLOGIA HUNGARICA},
	volume = {50},
	unique-id = {31975178},
	issn = {0133-5596},
	year = {2020},
	eissn = {1588-0230},
	pages = {178-178},
	orcid-numbers = {Varró, András/0000-0003-0745-3603}
}