Document Detail

The effect of length range on heat rate and power during shortening near in situ length in frog muscle.
MedLine Citation:
PMID:  2940260     Owner:  NLM     Status:  MEDLINE    
Heat rate and tension were measured during the steady state of isovelocity shortening in frog sartorius muscles at two speeds (7.5 and 2.0 mm s-1) through two ranges of the length-tension curve: 1.11 to 1.01 L0 and 1.01 to 0.91 L0. Both heat rate and mechanical power were higher at short length than at long length. The ratio of mechanical power to total energy rate was smaller at short length. The difference in heat rates in the two length ranges was greatest during shortening at 7.5 mm s-1 and least during isometric contractions. Calculations were made for two extreme interpretations of the results, based on the assumption that 30% of the isometric maintenance heat rate at optimum length is produced by processes related to activation: that all the difference in heat rate results from effects of length on activation processes and that all the difference results from effects on contractile processes. The rate of heat production by activation processes would have to be 1.5 times higher at short than at long length in an isometric contraction, 1.7 times higher during shortening at 2mm s-1 and 2.0 times higher at 7.5 mm s-1 to explain the differences in heat rate. The rate of contractile processes would have to be only 1.2 times higher at short than at long length. The results favour the interpretation that the contractile process itself is sensitive to sarcomere length near the plateau of the length-tension curve.(ABSTRACT TRUNCATED AT 250 WORDS)
S H Gilbert
Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of muscle research and cell motility     Volume:  7     ISSN:  0142-4319     ISO Abbreviation:  J. Muscle Res. Cell. Motil.     Publication Date:  1986 Apr 
Date Detail:
Created Date:  1986-06-30     Completed Date:  1986-06-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8006298     Medline TA:  J Muscle Res Cell Motil     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  115-21     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Actomyosin / analysis
Adenosine Triphosphatases / analysis
Hot Temperature*
Isometric Contraction
Muscle Contraction*
Rana pipiens
Time Factors
Reg. No./Substance:
9013-26-7/Actomyosin; EC 3.6.1.-/Adenosine Triphosphatases

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

Previous Document:  The effect of low ATP concentrations on relaxation in the myosin regulated myofibrils from scallop.
Next Document:  The ATPase kinetics of insect fibrillar flight muscle myosin subfragment-1.