Document Detail

Filament lattice of frog striated muscle. Radial forces, lattice stability, and filament compression in the A-band of relaxed and rigor muscle.
MedLine Citation:
PMID:  3264728     Owner:  NLM     Status:  MEDLINE    
Repulsive pressure in the A-band filament lattice of relaxed frog skeletal muscle has been measured as a function of interfilament spacing using an osmotic shrinking technique. Much improved chemical skinning was obtained when the muscles were equilibrated in the presence of EGTA before skinning. The lattice shrank with increasing external osmotic pressure. At any specific pressure, the lattice spacing in relaxed muscle was smaller than that of muscle in rigor, except at low pressures where the reverse was found. The lattice spacing was the same in the two states at a spacing close to that found in vivo. The data were consistent with an electrostatic repulsion over most of the pressure range. For relaxed muscle, the data lay close to electrostatic pressure curves for a thick filament charge diameter of approximately 26 nm, suggesting that charges stabilizing the lattice are situated about midway along the thick filament projections (HMM-S1). At low pressures, observed spacings were larger than calculated, consistent with the idea that thick filament projections move away from the filament backbone. Under all conditions studied, relaxed and rigor, at short and very long sarcomere lengths, the filament lattice could be modeled by assuming a repulsive electrostatic pressure, a weak attractive pressure, and a radial stiffness of the thick filaments (projections) that differed between relaxed and rigor conditions. Each thick filament projection could be compressed by approximately 5 or 2.6 nm requiring a force of 1.3 or 80 pN for relaxed and rigor conditions respectively.
B M Millman; T C Irving
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Biophysical journal     Volume:  54     ISSN:  0006-3495     ISO Abbreviation:  Biophys. J.     Publication Date:  1988 Sep 
Date Detail:
Created Date:  1989-02-22     Completed Date:  1989-02-22     Revised Date:  2010-09-09    
Medline Journal Info:
Nlm Unique ID:  0370626     Medline TA:  Biophys J     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  437-47     Citation Subset:  IM    
Department of Physics, University of Guelph, Ontario, Canada.
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MeSH Terms
Models, Theoretical
Muscle Contraction*
Muscle Relaxation*
Muscles / physiology*,  ultrastructure
Myofibrils / physiology*
Osmolar Concentration
Rana pipiens
Sarcomeres / physiology*,  ultrastructure

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

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