Light diffraction studies of active muscle fibres as a function of sarcomere length

1981 ◽  
Vol 2 (2) ◽  
pp. 215-224 ◽  
Author(s):  
Toshiharu Oba ◽  
Ronald J. Baskin ◽  
Richard L. Lieber
Keyword(s):  
Sarcomere Length ◽  
Light Diffraction ◽  
Muscle Fibres ◽  
Active Muscle

Storage and release of mechanical energy by active muscle: a non-elastic mechanism?

1985 ◽  
Vol 115 (1) ◽  
pp. 79-87 ◽  
Author(s):  
G. A. Cavagna ◽  
M. Mazzanti ◽  
N. C. Heglund ◽  
G. Citterio
Keyword(s):  
Isometric Contraction ◽  
Sarcomere Length ◽  
Mechanical Energy ◽  
Frog Muscle ◽  
Muscle Fibres ◽  
Elastic Recoil ◽  
Active Muscle ◽  
A Value ◽  
Elastic Mechanism ◽  
Isotonic Shortening

In frog muscle fibres, tetanically stimulated at a sarcomere length of about 2 micron, stretched at a velocity of 1 lengths-1 and released against a force equal to the maximum isometric, P0, a phase of rapid isotonic shortening takes place after release. As the amplitude of the stretch is increased from 1.5 to 9% of the initial length: (1) the amount of rapid isotonic shortening increases up to 9–10 nm per half sarcomere and (2) the stiffness of the fibre (an indication of the number of bridges attached) decreases to a value about equal to that measured during an isometric contraction. If a 5–10 ms delay is left between the end of stretch and release, the amount of rapid isotonic shortening increases to about 12 nm hs-1. A 300–500 ms delay, however, results in a decrease in rapid isotonic shortening to about 5 nm hs-1 and also results in a velocity transients against P0 that are similar to those described during release from a state of isometric contraction. It is concluded that the force attained after large, fast stretches is due to a greater force developed by each bridge and not to a greater number of bridges. After the elastic recoil (when the force is suddenly reduced to P0), these strained bridges are able to shorten by about 12 nm hs-1, suggesting that, during and immediately after stretching, they are charged to levels of potential energy greater than those attained in an isometric contraction.

An Electron Microscopic Study of the Muscle-fibres of the Diaphragm

1951 ◽  
Vol s3-92 (19) ◽  
pp. 323-332
Author(s):  
M. M. BLUHM ◽  
C. SITARAMAYYA
Keyword(s):  
Sarcomere Length ◽  
Muscle Fibres ◽  
Striated Muscles ◽  
Rat Diaphragm ◽  
Electron Microscopic ◽  
Adult Type ◽  
Isotonic Contraction ◽  
Acetyl Choline ◽  
Adult Rat ◽  
Passive Stretching

Myofibrils of rat diaphragm of various ages, in different states of activity, after denervation, and after acetyl choline contracture, were studied by electron microscopy. A comparative study of other rodent diaphragms and of human diaphragm was also made. Myofibrils from diaphragm are similar to those of other striated muscles. The differentiation into A and I bands is due to differences in the substance present round the actomyosin filaments in those regions. The Z disk is extra-sarcomere; it-appears even before any differentiation of the fibril into A and I bands is recognizable. At the age of about 42 days, the myofibrils in rat diaphragm are completely differentiated and conform tothe adult type. The sarcomere length in adult rat diaphragm is between 2 and 3 µ. The adult rat diaphragm contains two types of fibrils which differ, though not sharply, in their extensibility and thickness. The A and I bands react differently to a variety of stimuli. Thus, passive stretching affects the I band almost exclusively, while contraction affects both bands; here, again, the effect depends on the type of contraction; isotonic contraction shortens both A and I, whereas isometric contraction shortens A and lengthens I. In the denervated muscle the A band is shortened. On thewhole, the A band seems to play the major role in contraction. The H disk is intra-sarcomere and appears during contraction, especially when the muscle is stimulated in the stretched state. The M and N lines also are intra-sarcomere. Evidence regarding their nature and appearance is discussed.

scholarly journals Sarcomere-length dependence of myosin filament structure in skeletal muscle fibres of the frog

2014 ◽  
Vol 592 (5) ◽  
pp. 1119-1137 ◽  
Author(s):  
Massimo Reconditi ◽  
Elisabetta Brunello ◽  
Luca Fusi ◽  
Marco Linari ◽  
Manuel Fernandez Martinez ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Sarcomere Length ◽  
Myosin Filament ◽  
Muscle Fibres ◽  
Length Dependence ◽  
Filament Structure ◽  
Skeletal Muscle Fibres
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