scholarly journals Sarcomere length-dependent Ca2+ activation in skinned rabbit psoas muscle fibers: coordinated regulation of thin filament cooperative activation and passive force

2011 ◽  
Vol 61 (6) ◽  
pp. 515-523 ◽  
Author(s):  
Norio Fukuda ◽  
Takahiro Inoue ◽  
Mitsunori Yamane ◽  
Takako Terui ◽  
Fuyu Kobirumaki ◽  
...  
Keyword(s):  
Thin Filament ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Passive Force ◽  
Rabbit Psoas ◽  
Coordinated Regulation ◽  
Cooperative Activation

scholarly journals Differences in the Charge Distribution of Glycerol-Extracted Muscle Fibers in Rigor, Relaxation, and Contraction

1974 ◽  
Vol 64 (5) ◽  
pp. 551-567 ◽  
Author(s):  
Suzanne M. Pemrick ◽  
Charles Edwards
Keyword(s):  
Charge Distribution ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Nonlinear Relationship ◽  
Thin Filaments ◽  
Rabbit Psoas ◽  
Relaxation Solution ◽  
The Difference ◽  
Rest Length

Glycerol-extracted rabbit psoas muscle fibers were impaled with KCl-filled glass microelectrodes. For fibers at rest-length, the potentials were significantly more negative in solutions producing relaxation than in solutions producing either rigor or contraction; further the potentials in the latter two cases were not significantly different. For stretched fibers, with no overlap between thick and thin filaments, the potentials did not differ in the rigor, the relaxation, or the contraction solutions. The potentials measured from fibers in rigor did not vary significantly with the sarcomere length. For relaxed fibers, however, the potential magnitude decreased with increasing sarcomere length. The difference between the potentials measured for rigor and relaxed fibers exhibited a nonlinear relationship with sarcomere length. The potentials from calcium-insensitive fibers were less negative in both the rigor and the relaxation solutions than those from normal fibers. When calcium-insensitive fibers had been incubated in Hasselbach and Schneider's solution plus MgCl2 or Guba-Straub's solution plus MgATP the potentials recorded upon impalement were similar in the rigor and the relaxation solution to those obtained from normal fibers in the relaxed state. It is concluded that the increase in the negative potential as the glycerinated fiber goes from rigor to relaxation may be due to an alteration in the conformation of the contractile proteins in the relaxed state.

scholarly journals CONTRACTILITY AND ULTRASTRUCTURE IN GLYCEROL-EXTRACTED MUSCLE FIBERS

1965 ◽  
Vol 27 (1) ◽  
pp. 35-46 ◽  
Author(s):  
Frits Carlsen ◽  
Franklin Fuchs ◽  
Gustav G. Knappeis
Keyword(s):  
Electron Microscopy ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Ultrastructural Changes ◽  
Rabbit Psoas ◽  
Before And After ◽  
Ultrastructural Appearance ◽  
Isotonic Shortening ◽  
Rest Length

Glycerol-extracted rabbit psoas muscle fibers were examined by electron microscopy both before and after ATP-induced isotonic shortening. Ultrastructural changes were correlated with the initial sarcomere length and the degree of shortening. The ultrastructural appearance of the resting fiber at rest length was identical with that described by H. E. Huxley and Hanson. At sarcomere lengths greater than 3.7 to 3.8 µ, the A and I filaments were detached and separated by a gap. The presence of "gap" filaments was confirmed, and evidence is presented which indicates that these filaments form connections between the ends of the A and I filaments. Shortening from initial sarcomere lengths at which the filaments overlapped took place through sliding of the filaments. If shortening was initiated from sarcomere lengths at which there was a gap, a narrowing of the I band was brought about by a curling of the I filaments at the boundary between the A and I bands. No evidence could be found that the I filaments moved into the A band.

scholarly journals CONTRACTILITY AND ULTRASTRUCTURE IN GLYCEROL-EXTRACTED MUSCLE FIBERS

1965 ◽  
Vol 27 (1) ◽  
pp. 25-34 ◽  
Author(s):  
Frits Carlsen ◽  
Franklin Fuchs ◽  
Gustav G. Knappeis
Keyword(s):  
Electron Microscopy ◽  
Sarcomere Length ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Initial Length ◽  
Electron Microscopic ◽  
Apparent Contradiction ◽  
Tension Generation ◽  
Develop Tension ◽  
Isotonic Shortening

This study was undertaken to determine whether glycerol-extracted rabbit psoas muscle fibers can develop tension and shorten after being stretched to such a length that the primary and secondary filaments no longer overlap. A method was devised to measure the initial sarcomere length and the ATP-induced isotonic shortening in prestretched isolated fibers subjected to a small preload (0.02 to 0.15 P0). At all degrees of stretch, the fiber was able to shorten (60 to 75 per cent): to a sarcomere length of 0.7 µ when the initial length was 3.7 µ or less, and to an increasing length of 0.9 to 1.8 µ with increasing initial sarcomere length (3.8 to 4.4 µ). At sarcomere lengths of 3.8 to 4.5 µ, overlap of filaments was lost, as verified by electron microscopy. The variation in sarcomere length within individual fibers has been assessed by both light and electron microscopic measurements. In fibers up to 10 mm in length the stretch was evenly distributed along the fiber, and with sarcomere spacings greater than 4 µ there was only a slight chance of finding sarcomeres with filament overlap. These observations are in apparent contradiction to the assumption that an overlap of A and I filaments is necessary for tension generation and shortening.

STEP SIZE IN ACTIVATED RABBIT SARCOMERES IS INDEPENDENT OF FILAMENT OVERLAP

2004 ◽  
Vol 04 (04) ◽  
pp. 485-498 ◽  
Author(s):  
EKATERINA M. NAGORNYAK ◽  
GERALD H. POLLACK ◽  
FELIX A. BLYAKHMAN
Keyword(s):  
Molecular Structure ◽  
High Resolution ◽  
Molecular Mechanism ◽  
Thin Filament ◽  
Sarcomere Length ◽  
Psoas Muscle ◽  
Length Change ◽  
Step Size ◽  
Resolution Algorithm ◽  
Parallel Measurements

Investigations carried out on single cardiac and bumblebee myofibrils have shown stepwise sarcomere-length change of ~2.7 nm.1 We have carried out parallel measurements on single myofibrils from rabbit psoas muscle. Activated specimens were released or stretched using a motor-imposed ramp. With a high-resolution algorithm, we found that step sizes were always integer multiples of 2.7 nm, whether the length change was positive or negative, and independent of ramp velocity. Also, the influence of initial sarcomere length was studied, and found to be negligible. The value 2.7 nm, seen consistently, is equal to the linear repeat of actin monomers along the thin filament, a result that ties dynamical events to molecular structure, and places narrow constraints on any proposed molecular mechanism.

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