Document Detail


Local control of excitation-contraction coupling in human embryonic stem cell-derived cardiomyocytes.
MedLine Citation:
PMID:  19404384     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We investigated the mechanisms of excitation-contraction (EC) coupling in human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and fetal ventricular myocytes (hFVMs) using patch-clamp electrophysiology and confocal microscopy. We tested the hypothesis that Ca(2+) influx via voltage-gated L-type Ca(2+) channels activates Ca(2+) release from the sarcoplasmic reticulum (SR) via a local control mechanism in hESC-CMs and hFVMs. Field-stimulated, whole-cell [Ca(2+)](i) transients in hESC-CMs required Ca(2+) entry through L-type Ca(2+) channels, as evidenced by the elimination of such transients by either removal of extracellular Ca(2+) or treatment with diltiazem, an L-type channel inhibitor. Ca(2+) release from the SR also contributes to the [Ca(2+)](i) transient in these cells, as evidenced by studies with drugs interfering with either SR Ca(2+) release (i.e. ryanodine and caffeine) or reuptake (i.e. thapsigargin and cyclopiazonic acid). As in adult ventricular myocytes, membrane depolarization evoked large L-type Ca(2+) currents (I(Ca)) and corresponding whole-cell [Ca(2+)](i) transients in hESC-CMs and hFVMs, and the amplitude of both I(Ca) and the [Ca(2+)](i) transients were finely graded by the magnitude of the depolarization. hESC-CMs exhibit a decreasing EC coupling gain with depolarization to more positive test potentials, "tail" [Ca(2+)](i) transients upon repolarization from extremely positive test potentials, and co-localized ryanodine and sarcolemmal L-type Ca(2+) channels, all findings that are consistent with the local control hypothesis. Finally, we recorded Ca(2+) sparks in hESC-CMs and hFVMs. Collectively, these data support a model in which tight, local control of SR Ca(2+) release by the I(Ca) during EC coupling develops early in human cardiomyocytes.
Authors:
Wei-Zhong Zhu; Luis F Santana; Michael A Laflamme
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2009-04-30
Journal Detail:
Title:  PloS one     Volume:  4     ISSN:  1932-6203     ISO Abbreviation:  PLoS ONE     Publication Date:  2009  
Date Detail:
Created Date:  2009-04-30     Completed Date:  2009-08-07     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  101285081     Medline TA:  PLoS One     Country:  United States    
Other Details:
Languages:  eng     Pagination:  e5407     Citation Subset:  IM    
Affiliation:
Department of Pathology, University of Washington, Seattle, Washington, United States of America.
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MeSH Terms
Descriptor/Qualifier:
Calcium / metabolism
Calcium Channels, L-Type / metabolism*
Cells, Cultured
Electrophysiology
Embryonic Stem Cells / cytology*,  physiology
Humans
Membrane Potentials
Myocardial Contraction*
Myocytes, Cardiac / cytology,  physiology*
Sarcoplasmic Reticulum / metabolism
Grant Support
ID/Acronym/Agency:
HL064387/HL/NHLBI NIH HHS; HL080431/HL/NHLBI NIH HHS; HL085686/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Calcium Channels, L-Type; 7440-70-2/Calcium
Comments/Corrections

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