Document Detail

Excitation-contraction coupling in neonatal and adult myocardium of cat.
MedLine Citation:
PMID:  7081455     Owner:  NLM     Status:  MEDLINE    
Neonatal cardiac cells were smaller in diameter, having a lower concentration of myofilaments than cardiac cells of the adult cat. The sarcoplasmic reticulum-content in 1-day-old neonates was less than in the adult, and there were no transverse tubules in the neonatal myocardium. Postextrasystolic potentiation and post-voltage clamp potentiation were significantly greater in the adult than in the neonate. Rate inotropisms consisted of a fast component (1st 6-8 beats) and a slow component (50-100 beats). The beat constants for the decay of postextrasystolic potentiation and of the fast component of a negative frequency staircase were the same in both neonate and adult. The restitution of contractility was much faster in the neonate than in the adult. Shortening of the action potential plateau suppressed twitch tension in the first beat with little further effect on subsequent shortened beats in the neonate. The structural and functional differences between the neonate and adult lead to the conclusion that two sources of activator calcium contribute to the development of tension in mammalian ventricle.
J G Maylie
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The American journal of physiology     Volume:  242     ISSN:  0002-9513     ISO Abbreviation:  Am. J. Physiol.     Publication Date:  1982 May 
Date Detail:
Created Date:  1982-07-08     Completed Date:  1982-07-08     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0370511     Medline TA:  Am J Physiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  H834-43     Citation Subset:  IM    
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MeSH Terms
Action Potentials
Animals, Newborn / physiology*
Electric Stimulation
Membrane Potentials
Myocardial Contraction*
Papillary Muscles / physiology,  ultrastructure
Time Factors
Grant Support
5T01-GM-00538/GM/NIGMS NIH HHS; 6M0038//PHS HHS

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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