Document Detail

The capillary membrane and calcium kinetics in perfused hearts: independence of force decay on heart rate.
MedLine Citation:
PMID:  7127356     Owner:  NLM     Status:  MEDLINE    
Earlier studies have indicated there is no correlation between heart rate (HR) and force decay during Ca depletion. However a compelling hypothesis states that because the sarcolemma is in an intrinsically different state during the action potential than between action potentials, the release of Ca, and hence the decay of force, during Ca depletion should depend on the proportion of time spent in the depolarised state and hence should depend on HR. In each of ten Langendorff-perfused rabbit hearts we measured the exponential rate constant for the decline of activity developed force at two different heart rates. Heart rates were in the range of 48 to 142 beats . min-1. Application of the t test to the pairs of rate constants showed the difference within pairs to be not different from zero (P greater than 0.10). In order to explain this contradiction of the hypothesis, we considered that the capillary membrane limits Ca washout and hence force decay. To examine this, advantage was taken of the variation in rate constants between hearts (0.023 to 0.114 s-1). Linear regression of force decay rate constants with resistance to flow (perfusion pressure/flow rate), upon which capillary exchange area might be expected to depend, yielded a correlation coefficient of -0.494, on application of the t test, significant at P = 0.05. This correlation, we believe, supports the concept that the capillary membrane limits Ca washout and therefore that Ca-kinetic events related to force development (eg, HR dependence) are "hidden" behind the capillary membrane.
J T Saari
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Cardiovascular research     Volume:  16     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  1982 Aug 
Date Detail:
Created Date:  1982-12-18     Completed Date:  1982-12-18     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  417-22     Citation Subset:  IM    
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MeSH Terms
Calcium / metabolism*
Capillary Permeability
Coronary Circulation
Heart Rate*
Myocardial Contraction*
Myocardium / metabolism
Sarcolemma / metabolism
Grant Support
2-507-RR05407/RR/NCRR NIH HHS
Reg. No./Substance:

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

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