scholarly journals The effect of the lattice spacing change on cross-bridge kinetics in chemically skinned rabbit psoas muscle fibers. II. Elementary steps affected by the spacing change

1993 ◽  
Vol 64 (1) ◽  
pp. 197-210 ◽  
Author(s):  
Y. Zhao ◽  
M. Kawai
Keyword(s):  
Lattice Spacing ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Rabbit Psoas ◽  
Elementary Steps ◽  
Cross Bridge

BDM affects nucleotide binding and force generation steps of the cross-bridge cycle in rabbit psoas muscle fibers

1994 ◽  
Vol 266 (2) ◽  
pp. C437-C447 ◽  
Author(s):  
Y. Zhao ◽  
M. Kawai
Keyword(s):  
Equilibrium Constants ◽  
Muscle Fibers ◽  
Psoas Muscle ◽  
Isometric Tension ◽  
Activation Mechanism ◽  
Phosphate Binding ◽  
Rabbit Psoas ◽  
Cross Bridge ◽  
The Cross ◽  
Cross Bridges

The effect of 2,3-butanedione monoxime (BDM) on elementary steps of the cross-bridge cycle was studied with the sinusoidal analysis technique in skinned rabbit psoas muscle fibers. Our results showed that isometric tension and stiffness decreased progressively with an increase in the BDM concentration. The MgATP and MgADP binding constants increased 27 and 6 times, respectively, when BDM was increased from 0 to 18 mM, whereas the phosphate binding constant did not change significantly. The equilibrium constants of the ATP isomerization and detachment step were not sensitive to BDM, whereas the equilibrium constant of the attachment (power stroke) step decreased with BDM. Thus, in the presence of BDM, the number of attached cross bridges decreases; more cross bridges accumulate in the detached state, causing isometric tension and stiffness to decline. However, our detailed analysis shows that the decrease in the number of attached cross bridges is approximately 40%, which is not adequate to account for the 84% decrease in the isometric tension when 18 mM BDM was present. Therefore we suggest that a thin-filament activation mechanism is also affected by BDM.

Cross-bridge movement in glycerinated rabbit psoas muscle fibers

Biochemistry ◽  
1979 ◽  
Vol 18 (6) ◽  
pp. 959-963 ◽  
Author(s):  
Yu-Chih Chen Chiao ◽  
William F. Harrington
Keyword(s):  
Muscle Fibers ◽  
Psoas Muscle ◽  
Rabbit Psoas ◽  
Cross Bridge

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.

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