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001-es BibID:	BIBFORM032928
035-os BibID:	WOS:000225354300015
Első szerző:	Magyar János (élettanász)
Cím:	Divergent action potential morphologies reveal nonequilibrium properties of human cardiac Na channels / János Magyar, Carmen E. Kiper, Robert Dumaine, Don E. Burgess, Tamás Bányász, Jonathan Satin
Dátum:	2004
ISSN:	0008-6363
Megjegyzések:	Objective: Fast inward Na current (INa) carried by the voltage-gated Na channel (NaV1.5) is critical for action potential (AP) propagation and the rapid upstroke of the cardiac AP. In addition, a small fraction of NaV1.5 channels remains open throughout the plateau of the AP, and this current is termed as late INa. In patients with mutant NaV1.5-based congenital long Q?T (LQT) syndrome, mutant channels pass more late INa compared to wild-type channels in unaffected patients. Although LQT mutant NaV1.5 channels are well studied, there is no careful evaluation of the effects of cardiac APs on early and late current. This is important with the recent documentation of nonequilibrium INa.Methods: We measured AP-stimulated INa through NaV1.5 wild-type and two LQT mutant channels (?KPQ and N1325S). Three distinct AP morphologies were used: human embryonic stem cell-derived cardiac myocyte (hES-CM) APs with a relatively slow upstroke and canine endocardial and epicardial ventricular myocytes with rapid upstrokes.Results: All three APs elicited both early and late INa. For wild-type NaV1.5, the hES-CM AP elicits more early and late INa than either the endocardial or epicardial AP. The mechanism for this difference is that the hES-CM has a relative slow dV/dtmax that causes a maximal open channel probability. Slower upstroke stimulation also allows greater Na flux through wild-type and N1325S channels, but not the ?KPQ mutant.Conclusions: The inherent gating properties of NaV1.5 provide natural tuning of optimal INa density. Slower upstroke velocities can yield more INa and Na flux in some NaV1.5 variants.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	Cardiovascular Research. - 64 : 3 (2004), p. 477-487. -
További szerzők:	Kiper, Carmen E. Dumaine, Robert Burgess, Don E. Bányász Tamás (1960-) (élettanász) Satin, Jonathan
Pályázati támogatás:	OTKA-T043182 OTKA
Internet cím:	Szerző által megadott URL DOI Intézményi repozitóriumban (DEA) tárolt változat
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001-es BibID:	BIBFORM032937
035-os BibID:	PMID:17158651
Első szerző:	Schroder, Elizabeth
Cím:	Chronic verapamil treatment remodels ICa,L in mouse ventricle / Elizabeth Schroder, Janos Magyar, Don Burgess, Douglas Andres, Jonathan Satin
Dátum:	2007
ISSN:	0363-6135
Megjegyzések:	In this study we tested the hypothesis that ventricular homeostasis of L-type Ca(2+) current (I(Ca,L)) minimally involves regulation of the main pore-forming alpha-subunit (Ca(V)1.2) and auxiliary proteins that serve as positive or negative regulators of I(Ca,L). We treated animals for 24 h with verapamil (Ver, 3.6 mg.kg(-1).day(-1)), isoproterenol (Iso, 30 mg.kg(-1).day(-1)), or Iso + Ver via osmotic minipumps. To test for alterations of Ca(2+) channel complex components we performed real-time PCR and Western blot analysis on ventricle. In addition, cardiac myocytes (CMs) were dispersed and current was recorded in the whole cell configuration to evaluate I(Ca,L). Surprisingly, 24- to 48-h Ver increased Ca(V)1.2 mRNA and protein and I(Ca,L) current (Ver 11 +/- 1pA/pF vs. control 7 +/- 0.5pA/pF; P < 0.01). I(Ca,L) from CMs in Ver mice showed no change in whole cell capacitance. To examine the in vivo effects of a physiologically relevant Ca(2+) channel agonist, we treated mice with Iso. Twenty-four-hour Iso infusion increased heart rate; Ca(V)1.2- and Ca(V)beta(2) mRNA levels were constant, but the Ca(2+) channel subunit mRNA Rem was increased twofold. Cells isolated from 24-h Iso hearts showed no change in basal I(Ca,L) density and diminished responsiveness to acute 1 muM Iso. To further examine the homeostatic regulation of the Ca(2+) channel, we treated animals for 24 h with Iso + Ver. The influence of Iso + Ver was similar that of to Iso alone on Ca(2+) channel mRNAs and I(Ca,L), with the exception that it prevented the increase in Rem seen with Iso treatment. Long-term Ca(2+) channel blockade induces an increase of Ca(V)1.2 mRNA and protein and significantly increases I(Ca,L).
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	American Journal of Physiology-Heart And Circulatory Physiology 292 : 4 (2007), p. H1906-H1916. -
További szerzők:	Magyar János (1961-) (élettanász) Burgess, Don E. Andres, Douglas Satin, Jonathan
Internet cím:	DOI Intézményi repozitóriumban (DEA) tárolt változat
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