Calcium-dependence of Donnan potentials in glycerinated rabbit psoas muscle in rigor, at and beyond filament overlap; a role for titin in the contractile process

Cell Calcium ◽  
2011 ◽  
Vol 50 (1) ◽  
pp. 91-97 ◽  
Author(s):  
S.J. Coomber ◽  
E.M. Bartels ◽  
G.F. Elliott
Keyword(s):  
Psoas Muscle ◽  
Calcium Dependence ◽  
Rabbit Psoas

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 ANOMALOUS CONTRACTION OF INVERTEBRATE STRIATED MUSCLE

1965 ◽  
Vol 27 (3) ◽  
pp. 639-649 ◽  
Author(s):  
R. E. Stephens
Keyword(s):  
Mass Distribution ◽  
Striated Muscle ◽  
Psoas Muscle ◽  
Homarus Americanus ◽  
Limulus Polyphemus ◽  
Polarization Microscopy ◽  
Trypsin Treatment ◽  
Rabbit Psoas ◽  
Ultraviolet Microbeam ◽  
Intrinsic Birefringence

The phenomenon of A band shortening or contraction has been investigated in glycerinated myofibrils of Pecten irradians, Homarus americanus, Cambarus virilis, and Limulus polyphemus through the techniques of ultraviolet microbeam inactivation and polarization microscopy. With the former method, it has been shown that these muscles, even though exhibiting the shortening effect, contract in a manner consistent with only the sliding filament model. Intrinsic birefringence studies have indicated no significant changes in mass distribution or orientation within the shortened A bands. Except in the case of Limulus muscle, the shortening effect was seen only in contraction under tension. The magnitude of this anomalous phenomenon was dependent upon glycerination time and has been duplicated in rabbit psoas muscle through brief trypsin treatment. A band shortening could not be observed in glutaraldehyde-fixed muscle or in myofibrils glycerinated for only short periods. It has been concluded that the phenomenon of A band contraction is an artifact induced by the glycerination procedure, possibly through weakening of the sarcomere structure. However, the fact that the A band shortens under tension rather than lengthens poses an interesting paradox.

scholarly journals Tropomyosin is in a reduced state in rabbit psoas muscle

2011 ◽  
Vol 32 (1) ◽  
pp. 19-21 ◽  
Author(s):  
Sherwin S. Lehrer ◽  
Socheata Ly ◽  
Franklin Fuchs
Keyword(s):  
Psoas Muscle ◽  
Rabbit Psoas ◽  
Reduced State
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