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001-es BibID:	BIBFORM051689
035-os BibID:	WOS:000326178500011
Első szerző:	Jost Norbert
Cím:	Ionic mechanisms limiting cardiac repolarization reserve in humans compared to dogs / Norbert Jost, László Virág, Philippe Comtois, Balázs Ördög, Viktória Szuts, György Seprényi, Miklós Bitay, Zsófia Kohajda, István Koncz, Norbert Nagy, Tamás Szél, János Magyar, Mária Kovács, László G. Puskás, Csaba Lengyel, Erich Wettwer, Ursula Ravens, Péter P. Nánási, Julius Gy. Papp, András Varró, Stanley Nattel
Dátum:	2013
ISSN:	0022-3751
Megjegyzések:	Abstract The species-specific determinants of repolarization are poorly understood. Thisstudy compared the contribution of various currents to cardiac repolarization in canine andhuman ventricle.Conventional microelectrode,whole-cell patch-clamp,molecular biological andmathematical modelling techniques were used. Selective IKr block (50?100 nmol l?1 dofetilide)lengthened AP duration at 90% of repolarization (APD90) >3-fold more in human than dog,suggesting smaller repolarization reserve in humans. Selective IK1 block (10 ?mol l?1 BaCl2) andIKs block (1 ?mol l?1 HMR-1556) increased APD90 more in canine than human right ventricularpapillary muscle. Ion current measurements in isolated cardiomyocytes showed that IK1 and IKsdensities were 3- and 4.5-fold larger in dogs than humans, respectively. IKr density and kineticswere similar in human versus dog. ICa and Ito were respectively ?30% larger and ?29% smallerin human, and Na+?Ca2+ exchange current was comparable. Cardiac mRNA levels for the main IK1 ion channel subunit Kir2.1 and the IKs accessory subunit minK were significantly lower, butmRNA expression of ERG and KvLQT1 (IKr and IKs ?-subunits) were not significantly different,in human versus dog. Immunostaining suggested lower Kir2.1 and minK, and higher KvLQT1protein expression in human versus canine cardiomyocytes. IK1 and IKs inhibition increased theAPD-prolonging effect of IKr block more in dog (by 56% and 49%, respectively) than human(34 and 16%), indicating that both currents contribute to increased repolarization reserve inthe dog. A mathematical model incorporating observed human?canine ion current differencesconfirmed the role of IK1 and IKs in repolarization reserve differences. Thus, humans show greaterrepolarization-delaying effects of IKr block than dogs, because of lower repolarization reservecontributions from IK1 and IKs, emphasizing species-specific determinants of repolarization andthe limitations of animal models for human disease.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban L-type calcium current action potential dog heart human heart repolarization
Megjelenés:	Journal of Physiology-London. - 591 : 17 (2013), p. 4189-4206. -
További szerzők:	Virág László (élettanász Szeged) Comtois, Philippe Ördög Balázs Szuts Viktória Seprényi György Bitay Miklós Kohajda Zsófia Koncz István (Szeged) Nagy Norbert (1977-) (kísérletes farmakológus) Szél Tamás Magyar János (1961-) (élettanász) Kovács Mária (Szeged) Puskás László G. Lengyel Csaba (Szeged) Wettwer, Erich Ravens, Ursula Nánási Péter Pál (1956-) (élettanász) Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus) Nattel, Stanley
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM009079
Első szerző:	Lengyel Csaba (Szeged)
Cím:	Role of slow delayed rectifier K+-current in QT prolongation in the alloxan-induced diabetic rabbit heart / Lengyel, C., Virag, L., Kovacs, P. P., Kristof, A., Pacher, P., Kocsis, E., Koltay, Z. M., Nanasi, P. P., Toth, M., Kecskemeti, V., Papp, J. G., Varro, A., Jost, N.
Dátum:	2008
ISSN:	1748-1716 (Electronic)
Megjegyzések:	In diabetes mellitus, several cardiac electrophysiological parameters are known to be affected. In rodent experimental diabetes models, changes in these parameters were reported, but only limited relevant information is available in other species, having cardiac electrophysiological properties more resembling the human, including the rabbit. The present study was designed to analyse the effects of experimental type 1 diabetes on ventricular repolarization and the underlying transmembrane potassium currents in rabbit hearts. METHODS: Diabetes was induced by a single injection of alloxan (145 mg kg(-1) i.v.). After the development of diabetes (3 weeks), electrophysiological studies were performed using whole cell voltage clamp and ECG measurements. RESULTS: The QT(c) interval in diabetic rabbits was moderately but statistically significantly longer than measured in the control animals (155 +/- 1.8 ms vs. 145 +/- 2.8 ms, respectively, n = 9-10, P < 0.05). This QT(c)-lengthening effect of diabetes was accompanied by a significant reduction in the density of the slow delayed rectifier K(+) current, I(Ks) (from 1.48 +/- 0.35 to 0.86 +/- 0.17 pA pF(-1) at +50 mV, n = 19-21, P < 0.05) without changes in current kinetics. No differences were observed either in the density or in the kinetics of the inward rectifier K(+) current (I(K1)), the rapid delayed rectifier K(+) current (I(Kr)), the transient outward current (I(to)) and the L-type calcium current (I(CaL)) between the control and alloxan-treated rabbits. CONCLUSION: It is concluded that type 1 diabetes mellitus, although only moderately, lengthens ventricular repolarization. Diabetes attenuates the repolarization reserve by decreasing the density of I(Ks) current, and thereby may enhance the risk of sudden cardiac death.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban Alloxan Animals Delayed Rectifier Potassium Channels Diabetes Mellitus, Experimental Electrocardiography Heart Heart Conduction System Heart Ventricles Long QT Syndrome Male Patch-Clamp Techniques Rabbits
Megjelenés:	Acta Physiologica (Oxford, England). - 192 : 3 (2008), p. 359-368. -
További szerzők:	Virág László (élettanász Szeged) Kovacs Péter Pál (Szeged) Kristóf A. (Szeged) Pacher Pál Kocsis E. Koltay Zs. M. Nánási Péter Pál (1956-) (élettanász) Tóth M. Kecskeméti Valéria Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus) Jost Norbert
Internet cím:	DOI elektronikus változat
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001-es BibID:	BIBFORM001024
Első szerző:	Lengyel Csaba (Szeged)
Cím:	Diabetes mellitus attenuates the repolarization reserve in mammalian heart / Lengyel Cs., Virág L., Bíró T., Jost N., Magyar J., Biliczki P., Kocsis E., Skoumal R., Nánási P.P., Tóth M., Kecskeméti V., Papp Gy. J., Varró A.
Dátum:	2007
ISSN:	0008-6363 (Print)
Megjegyzések:	In diabetes mellitus several cardiac electrophysiological parameters are known to be affected. In rodent experimental diabetes models changes in these parameters were reported, but no such data are available in other mammalian species including the dog. The present study was designed to analyse the effects of experimental type 1 diabetes on ventricular repolarization and its underlying transmembrane ionic currents and channel proteins in canine hearts. METHODS AND RESULTS: Diabetes was induced by a single injection of alloxan, a subgroup of dogs received insulin substitution. After the development of diabetes (8 weeks) electrophysiological studies were performed using conventional microelectrodes, whole cell voltage clamp, and ECG. Expression of ion channel proteins was evaluated by Western blotting. The QTc interval and the ventricular action potential duration in diabetic dogs were moderately prolonged. This was accompanied by significant reduction in the density of the transient outward K+ current (I(to)) and the slow delayed rectifier K+ current (I(Ks)), to 54.6% and 69.3% of control, respectively. No differences were observed in the density of the inward rectifier K+ current (I(K1)), rapid delayed rectifier K+ current (I(Kr)), and L-type Ca2+ current (I(Ca)). Western blot analysis revealed a reduced expression of Kv4.3 and MinK (to 25+/-21% and 48+/-15% of control, respectively) in diabetic dogs, while other channel proteins were unchanged (HERG, MiRP1, alpha(1c)) or increased (Kv1.4, KChIP2, KvLQT1). Insulin substitution fully prevented the diabetes-induced changes in I(Ks), KvLQT1 and MinK, however, the changes in I(to), Kv4.3, and Kv1.4 were only partially diminished by insulin. CONCLUSION: It is concluded that type 1 diabetes mellitus, although only moderately, lengthens ventricular repolarization, attenuates the repolarization reserve by decreasing I(to) and I(Ks) currents, and thereby may markedly enhance the risk of sudden cardiac death.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Cardiovascular Research 73 : 3 (2007), p. 512-520. -
További szerzők:	Virág László (élettanász Szeged) Bíró Tamás (1968-) (élettanász) Jost Norbert Magyar János (1961-) (élettanász) Biliczki Péter Kocsis E. Skoumal, R. Nánási Péter Pál (1956-) (élettanász) Tóth M. Kecskeméti Valéria Papp Gy. Julius (Szeged) Varró András (1954-) (farmakológus, klinikai farmakológus)
Internet cím:	elektronikus változat elektronikus változat DOI
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