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001-es BibID:	BIBFORM037325
Első szerző:	Magyar János (élettanász)
Cím:	Rem-GTPase regulates cardiac myocyte L-type calcium current / Magyar J., Kiper C. E., Sievert G., Cai W., Shi G. X., Crump S. M., Li L., Niederer S., Smith N., Andres D. A., Satin J.
Dátum:	2012
Megjegyzések:	Rationale: The L-type calcium channels (LTCC) are critical for maintaining Ca ( 2+) -homeostasis. In heterologous expression studies, the RGK-class of Ras-related G-proteins regulates LTCC function; however, the physiological relevance of RGK-LTCC interactions is untested. Objective: In this report we test the hypothesis that the RGK protein, Rem, modulates native Ca ( 2+) current (ICa,L) via LTCC in murine cardiomyocytes. Methods and Results: Rem knockout mice (Rem (-/-) ) were engineered, and ICa,L and Ca ( 2+) -handling properties were assessed. Rem (-/-) ventricular cardiomyocytes displayed increased ICa,L density. ICa,L activation was shifted positive on the voltage axis, and β-adrenergic stimulation normalized this shift compared with wild-type ICa,L. Current kinetics, steady-state inactivation, and facilitation was unaffected by Rem (-/-) . Cell shortening was not significantly different. Increased ICa,L density in the absence of frank phenotypic differences motivated us to explore putative compensatory mechanisms. Despite the larger ICa,L density, Rem (-/-) cardiomyocyte Ca ( 2+) twitch transient amplitude was significantly less than that compared with wild type. Computer simulations and immunoblot analysis suggests that relative dephosphorylation of Rem (-/-) LTCC can account for the paradoxical decrease of Ca ( 2+) transients. Conclusions: This is the first demonstration that loss of an RGK protein influences ICa,L in vivo in cardiac myocytes.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban monomer G-protein heart calcium channel
Megjelenés:	Channels 6 : 3 (2012), p. 166-173. -
További szerzők:	Kiper, Carmen E. Sievert, Gail Cai, Weikang Shi, Geng-Xian Crump, Shawn M. Li, Liren Niederer, Steven Smith, Nic Andres, Douglas Satin, Jonathan
Internet cím:	Intézményi repozitóriumban (DEA) tárolt változat DOI
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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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