Document Detail


Effects of acidosis on force-sarcomere length and force-velocity relations of rat cardiac muscle.
MedLine Citation:
PMID:  3708645     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The effect of hypercapnic acidosis was compared with that of lowering extracellular calcium concentration ([Ca++]o) in rat cardiac trabeculae. The relations between force and sarcomere length and between force and velocity were studied. Sarcomere length was measured by means of laser diffraction techniques and sarcomere shortening velocity by means of isovelocity releases. The curve representing the relation between force and sarcomere length shifted from convex towards the ordinate (pH 7.35) to convex towards the abscissa (pH 6.68) as after [Ca++]o had been reduced from 1.5 to 0.3 mmol X litre-1. Increasing [Ca++]o at low pH from 1.5 to 4.0 mmol X litre-1 allowed the shape of the relation to be restored, but force values failed to return to control values. The relation between force and pH over the range 6.22-7.94 was also tested. During steady low pH maximum unloaded sarcomere shortening velocity was not significantly different from control values whereas it was decreased at low [Ca++]o. Under both conditions maximum isometric tension (Po) was reduced. The results are consistent with the hypothesis that H+ ions cause a shift of the force-p Ca curve to the right at all sarcomere lengths, as a result of competition between Ca++ and H+ ions for binding to the myofilaments.
Authors:
L Ricciardi; J J Bucx; H E ter Keurs
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cardiovascular research     Volume:  20     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  1986 Feb 
Date Detail:
Created Date:  1986-06-30     Completed Date:  1986-06-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  117-23     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Acidosis, Respiratory / physiopathology*
Animals
Calcium / physiology
Heart / physiopathology*
Hydrogen-Ion Concentration
Hypercapnia / physiopathology
Myocardial Contraction*
Myofibrils / physiology*
Rats
Rats, Inbred Strains
Sarcomeres / physiology*
Chemical
Reg. No./Substance:
7440-70-2/Calcium

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


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