Kinetics of Myoblast Proliferation Show That Resident Satellite Cells Are Competent to Fully Regenerate Skeletal Muscle Fibers

2002 ◽  
Vol 281 (1) ◽  
pp. 39-49 ◽  
Author(s):  
P Zammit
Keyword(s):  
Skeletal Muscle ◽  
Satellite Cells ◽  
Muscle Fibers ◽  
Skeletal Muscle Fibers ◽  
Myoblast Proliferation ◽  
Kinetics Of

Determinants of relaxation rate in skinned frog skeletal muscle fibers

1998 ◽  
Vol 274 (6) ◽  
pp. C1608-C1615 ◽  
Author(s):  
Philip A. Wahr ◽  
J. David Johnson ◽  
Jack. A. Rall
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Slow Phase ◽  
Frog Skeletal Muscle ◽  
Force Of Contraction ◽  
Thin Filaments ◽  
Fast Phase ◽  
Skeletal Muscle Fibers ◽  
Kinetics Of ◽  
Overall Kinetics

The influences of sarcomere uniformity and Ca2+ concentration on the kinetics of relaxation were examined in skinned frog skeletal muscle fibers induced to relax by rapid sequestration of Ca2+ by the photolysis of the Ca2+ chelator, diazo-2, at 10°C. Compared with an intact fiber, diazo-2-induced relaxation exhibited a faster and shorter initial slow phase and a fast phase with a longer tail. Stabilization of the sarcomeres by repeated releases and restretches during force development increased the duration of the slow phase and slowed its kinetics. When force of contraction was decreased by lowering the Ca2+concentration, the overall kinetics of relaxation was accelerated, with the slow phase being the most sensitive to Ca2+ concentration. Twitchlike contractions were induced by photorelease of Ca2+ from a caged Ca2+ (DM-Nitrophen), with subsequent Ca2+ sequestration by intact sarcoplasmic reticulum or Ca2+ rebinding to caged Ca2+. These twitchlike responses exhibited relaxation kinetics that were about twofold slower than those observed in intact fibers. Results suggest that the slow phase of relaxation is influenced by the degree of sarcomere homogeneity and rate of Ca2+ dissociation from thin filaments. The fast phase of relaxation is in part determined by the level of Ca2+ activation.

scholarly journals Kinetics of contractile activation in voltage clamped frog skeletal muscle fibers

1997 ◽  
Vol 73 (4) ◽  
pp. 1999-2011 ◽  
Author(s):  
P. Szentesi ◽  
Z. Papp ◽  
G. Szücs ◽  
L. Kovács ◽  
L. Csernoch
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Frog Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Contractile Activation ◽  
Kinetics Of

Fall in intracellular Po 2 at the onset of contractions in Xenopus single skeletal muscle fibers

2001 ◽  
Vol 90 (5) ◽  
pp. 1871-1876 ◽  
Author(s):  
Michael C. Hogan
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibers ◽  
Ringer Solution ◽  
Work Period ◽  
Force Development ◽  
Delayed Onset ◽  
Maximal Force ◽  
Skeletal Muscle Fibers ◽  
Lumbrical Muscle ◽  
Kinetics Of

It remains uncertain whether the delayed onset of mitochondrial respiration on initiation of muscle contractions is related to O2 availability. The purpose of this research was to measure the kinetics of the fall in intracellular Po 2 at the onset of a contractile work period in rested and previously worked single skeletal muscle fibers. Intact single skeletal muscle fibers ( n = 11) from Xenopus laevis were dissected from the lumbrical muscle, injected with an O2-sensitive probe, mounted in a glass chamber, and perfused with Ringer solution (Po 2 = 32 ± 4 Torr and pH = 7.0) at 20°C. Intracellular Po 2 was measured in each fiber during a protocol consisting sequentially of 1-min rest; 3 min of tetanic contractions (1 contraction/2 s); 5-min rest; and, finally, a second 3-min contractile period identical to the first. Maximal force development and the fall in force (to 83 ± 2 vs. 86 ± 3% of maximal force development) in contractile periods 1 and 2, respectively, were not significantly different. The time delay (time before intracellular Po 2 began to decrease after the onset of contractions) was significantly greater ( P < 0.01) in the first contractile period (13 ± 3 s) compared with the second (5 ± 2 s), as was the time to reach 50% of the contractile steady-state intracellular Po 2(28 ± 5 vs. 18 ± 4 s, respectively). In Xenopus single skeletal muscle fibers, 1) the lengthy response time for the fall in intracellular Po 2 at the onset of contractions suggests that intracellular factors other than O2 availability determine the on-kinetics of oxidative phosphorylation and 2) a prior contractile period results in more rapid on-kinetics.

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