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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:	BIBFORM016885
Első szerző:	Virág László (élettanász Szeged)
Cím:	Analysis of the contribution of Ito to repolarization in canine ventricular myocardium / Virág L., Jost N., Papp R., Koncz I., Kristóf A., Kohajda Z., Harmati G., Carbonell-Pascual B., Ferrero J. M. Jr., Papp J. Gy., Nánási P. P., Varró A.
Dátum:	2011
ISSN:	0007-1188
Megjegyzések:	Contribution of the transient outward potassium current (Ito) to ventricular repolarization is controversial depending on the experimental conditions, the region of myocardium or the species studied. The aim of the present study was, therefore, to characterize Ito and estimate its contribution to repolarization reserve in canine ventricular myocardium. Experimental approach: Ion currents were recorded using conventional whole cell voltage clamp and action potential voltage clamp techniques in isolated canine ventricular cells. Action potentials were recorded from canine ventricular preparations using microelectrodes. Key results: Contribution of Ito to repolarization was studied using 100 ?M chromanol 293B in full IKs blockade by 0.5 ?M HMR 1556. This high concentration of chromanol 293B effectively suppressed Ito without affecting other repolarizing K(+) currents (IK1, IKr, Ip). Action potential clamp experiments revealed a slowly inactivating and a "late" chromanol-sensitive current component flowing during the action potential plateau. Action potentials were significantly lengthened by chromanol 293B in the presence of HMR 1556. This lengthening effect of Ito inhibition showed reverse rate-dependent properties. It was extremely augmented after additional attenuation of repolarization reserve by 0.1 ?M dofetilide resulting in the occurrence of early afterdepolarizations (EADs). The results have been confirmed by computer simulation. Conclusions and Implications: The results indicate that Ito is involved in governing repolarization in canine ventricular myocardium and, it contributes significantly to the repolarization reserve. Therefore, blockade of Ito may enhance proarrhythmic risk.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban transient outward current action potential duration repolarization reserve cardiac ventricular muscle arrhythmia
Megjelenés:	British Journal Of Pharmacology. - 164 : 1 (2011), p. 93-105. -
További szerzők:	Jost Norbert Papp R. Koncz István (Szeged) Kristóf A. (Szeged) Kohajda Zsófia Harmati Gábor (1983-) (élettanász) Carbonell-Pascual, B. Ferrero, J. M. Jr Papp Gy. Julius (Szeged) Nánási Péter Pál (1956-) (élettanász) Varró András (1954-) (farmakológus, klinikai farmakológus)
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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