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001-es BibID:	BIBFORM032929
Első szerző:	Satin, Jonathan
Cím:	Mechanism of spontaneous excitability in human embryonic stem cell derived cardiomyocytes / Jonathan Satin, Izhak Kehat, Oren Caspi, Irit Huber, Gil Arbel, Ilanit Itzhaki, Janos Magyar, Elizabeth A. Schroder, Ido Perlman, Lior Gepstein
Dátum:	2004
ISSN:	0022-3751
Megjegyzések:	Human embryonic stem cell-derived cardiomyocytes (hES-CMs) are thought to recapitulate the embryonic development of heart cells. Given the exciting potential of hES-CMs as replacement tissue in diseased hearts, we investigated the pharmacological sensitivity and ionic current of mid-stage hES-CMs (20?35 days post plating). A high-resolution microelectrode array was used to assess conduction in multicellular preparations of hES-CMs in spontaneously contracting embryoid bodies (EBs). TTX (10 ?m) dramatically slowed conduction velocity from 5.1 to 3.2 cm s?1 while 100 ?m TTX caused complete cessation of spontaneous electrical activity in all EBs studied. In contrast, the Ca2+ channel blockers nifedipine or diltiazem (1 ?m) had a negligible effect on conduction. These results suggested a prominent Na+ channel current, and therefore we patch-clamped isolated cells to record Na+ current and action potentials (APs). We found for isolated hES-CMs a prominent Na+ current (244 ? 42 pA pF?1 at 0 mV; n = 19), and a hyperpolarization-activated current (HCN), but no inward rectifier K+ current. In cell clusters, 3 ?m TTX induced longer AP interpulse intervals and 10 ?m TTX caused cessation of spontaneous APs. In contrast nifedipine (Ca2+ channel block) and 2 mm Cs+ (HCN complete block) induced shorter AP interpulse intervals. In single cells, APs stimulated by current pulses had a maximum upstroke velocity (dV/dtmax) of 118 ? 14 V s?1 in control conditions; in contrast, partial block of Na+ current significantly reduced stimulated dV/dtmax (38 ? 15 V s?1). RT-PCR revealed NaV1.5, CaV1.2, and HCN-2 expression but we could not detect Kir2.1. We conclude that hES-CMs at mid-range development express prominent Na+ current. The absence of background K+ current creates conditions for spontaneous activity that is sensitive to TTX in the same range of partial block of NaV1.5; thus, the NaV1.5 Na+ channel is important for initiating spontaneous excitability in hES-derived heart cells.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban külföldön készült közlemény
Megjelenés:	Journal of Physiology (London) 559 : 2 (2004), p. 479-496. -
További szerzők:	Kehat, Izhak Caspi, Oren Huber, Irit Arbel, Gil Itzhaki, Ilanit Magyar János (1961-) (élettanász) Schroder, Elizabeth Perlman, Ido Gepstein, Lior
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