| Contribution of the sodium-calcium exchanger to contractions in immature rabbit ventricular myocytes. | |
MedLine Citation:
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PMID: 9098848 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In immature cardiac myocytes, the sarcoplasmic reticulum is sparse. Thus, we hypothesized that sarcolemmal Ca2+ influx through Na(+)-Ca2+ exchange is the dominant mechanism for modulating intracellular Ca2+ during contractions in fetal and neonatal hearts. We measured Na(+)-Ca2+ exchange currents in neonatal and adult rabbit ventricular cells using a rapid solution switch into 0 mM external Na+. The current densities (mean +/- SEM) were larger in 8 neonatal cells than in 10 adult cells (5.4 +/- 1.38 versus 1.65 +/- 0.25 pA/pF). Intracellular Ca2+ transients after inhibiting the sarcoplasmic reticulum with ryanodine and thapsigargin were unchanged in 15 neonatal cells, but decreased in 15 adult cells to 78.9 +/- 5.6% of baseline. When the Ca2+ channels were also inhibited by adding nifedipine, Ca2+ transients from Na(+)-Ca2+ exchange were 30.0 +/- 3.5% of baseline in neonatal cells compared with 13.4 +/- 3.4% in adult cells. Simultaneous contractions were a larger percent of baseline in neonatal cells (85.7.6 +/- 6.4%) than in adult cells (78.9 +/- 5.6%) after inhibiting the sarcoplasmic reticulum, and were unmeasureable in many cells from both age groups after inhibiting the Ca2+ channels as well. The ratio of Na(+)-Ca2+ exchanger mRNA to sarcoplasmic reticulum Ca(2+)-ATPase mRNA levels decreased from 1.0 +/- 0.13 to 0.4 +/- 0.03 to 0.26 +/- 0.02 in fetal, neonatal and adult ventricles, respectively. These measurements were consistent with a dominant role for the Na(+)-Ca2+ exchanger in the immature heart. |
Authors:
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T K Chin; G A Christiansen; J G Caldwell; J Thorburn |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Pediatric research Volume: 41 ISSN: 0031-3998 ISO Abbreviation: Pediatr. Res. Publication Date: 1997 Apr |
Date Detail:
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Created Date: 1997-07-02 Completed Date: 1997-07-02 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0100714 Medline TA: Pediatr Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 480-5 Citation Subset: IM |
Affiliation:
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Department of Pediatrics, University of Utah Health Sciences Center, Salt Lake City 84113, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Animals, Newborn Calcium* Calcium Channel Blockers / pharmacology Carrier Proteins / physiology* Heart Ventricles / cytology, drug effects*, growth & development Myocardial Contraction / physiology* Patch-Clamp Techniques RNA, Messenger / metabolism Rabbits Sarcoplasmic Reticulum / drug effects*, metabolism Sodium* Sodium-Calcium Exchanger |
| Grant Support | |
ID/Acronym/Agency:
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HD27827/HD/NICHD NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Calcium Channel Blockers; 0/Carrier Proteins; 0/RNA, Messenger; 0/Sodium-Calcium Exchanger; 7440-23-5/Sodium; 7440-70-2/Calcium |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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