Document Detail

Adaptive control of cardiac contraction to changes in loading: from theory of sarcomere dynamics to whole-heart function.
MedLine Citation:
PMID:  21534019     Owner:  NLM     Status:  Publisher    
The heart accommodates to rapid changes in demands. This review elucidates the adaptive control of cardiac function by loading conditions, and integrates the sarcomeric control of contraction (SCC) with isolated trabeculae and in vivo whole-heart studies. The SCC includes two feedback mechanisms: (1) cooperativity that regulates cross-bridge (XB) recruitment and the force-length relationship, and (2) mechanical feedback, whereby the filament-sliding velocity determines the XB-weakening rate and the force-velocity relationship. An isolated rat trabeculae study tested the suggested mechanisms during sarcomeric lengthening. The observations indicate that lengthening decreases the XB-weakening rate in a velocity-dependent manner, congruent with the suggested hypothesis and in contrast to alternative theories. A whole-heart level study in sheep reveals the existence of a preload-independent linear relationship between the external work (EW) and pressure-time integral during transient vena cava occlusions, for any given afterload, and not just at isovolumic contractions. The slope of this relationship decreases as the afterload increases. These findings highlight the mechanisms underlying the pressure (Frank's phenomenon) and EW (Starling's phenomenon) generation and the roles that the preload and afterload play. The theoretical, isolated fibers and whole-heart studies provide complementary information that strengthens our understanding of cardiac function from the top-down and bottom-up.
Moran Yadid; Gali Sela; Daria Amiad Pavlov; Amir Landesberg
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-5-3
Journal Detail:
Title:  Pflugers Archiv : European journal of physiology     Volume:  -     ISSN:  1432-2013     ISO Abbreviation:  -     Publication Date:  2011 May 
Date Detail:
Created Date:  2011-5-2     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0154720     Medline TA:  Pflugers Arch     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Technion, Israel Institute of Technology, Haifa, 32000, Israel.
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