Document Detail


Calcium metabolism and depressed contractility in isolated human and porcine heart muscle.
MedLine Citation:
PMID:  1706179     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Contractility is often depressed in isolated heart muscle. To analyze this phenomenon, we measured the derivative of left ventricular pressure (dP/dt) in intact and in isolated, blood perfused pig hearts, and peak force (F) or stress (F/mm2) in ventricular trabeculae of man and pig. When the heart was in the steady state at a priming frequency of 2 Hz an extrasystolic interval of 0.3 s was interposed, followed by four postextrasystolic intervals of 0.8 s. In the case of isolated trabeculae the priming frequency was 0.2 Hz, the extra interval 0.4 s, and the post-extrasystolic intervals were 5 s. The exponential decay of potentiation is characterized by the constant D: a low value of D indicates a rapid decay of potentiation. DP/dt was about 1000 mm Hg/s in the intact hearts, but within 1 h after isolation dP/dt decreased to about 700 mm Hg/s, and this was associated with a decrease in D from 0.63 to 0.40. Developed stress in the isolated trabeculae was about 2 mN/mm2 and D was about 0.20 under standard, in vitro conditions (a.o. 1.5 mM Ca2+. 0.2 Hz stimulus frequency). This stress is only 10% of the calculated stress in the intact heart. An increase of priming frequency, or of [Ca2+], or addition of 30 nM isoproterenol to the perfusate caused a marked increase in F and D. Properties of human and porcine trabeculae were quantitatively similar. The strong correlation between dP/dt, or F, and D suggests a causal relationship. This is consistent with the current model of e-c coupling in heart muscle, in which the activity of the Ca2+ pump of the sarcoplasmic reticulum determines the decay of potentiation and the amount of releasable Ca2+ in the reticulum determines force of contraction. Since isoproterenol stimulates the Ca2+ pump in the reticulum, the increase in D and F induced by this drug is consistent with the model. We conclude, that the decreased dP/dt, F, and D in isolated preparations was due to impaired sarcoplasmic reticulum function. The role of this phenomenon in the stunned heart syndrome, species differences and possible causes are discussed.
Authors:
V J Schouten; J J Schipperheyn; G L van Rijk-Zwikker; G P Swier
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Basic research in cardiology     Volume:  85     ISSN:  0300-8428     ISO Abbreviation:  Basic Res. Cardiol.     Publication Date:    1990 Nov-Dec
Date Detail:
Created Date:  1991-04-18     Completed Date:  1991-04-18     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0360342     Medline TA:  Basic Res Cardiol     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  563-74     Citation Subset:  IM    
Affiliation:
Department of Thoracic Surgery, University of Leiden, The Netherlands.
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MeSH Terms
Descriptor/Qualifier:
Animals
Calcium / metabolism*
Cardiac Complexes, Premature / physiopathology
Electrophysiology
Heart / physiology*
Homeostasis
Humans
Isoproterenol / pharmacology
Myocardial Contraction*
Myocardium / metabolism*
Osmolar Concentration
Swine
Chemical
Reg. No./Substance:
7440-70-2/Calcium; 7683-59-2/Isoproterenol

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


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