Neurotrophic control of the transmembrane Cl? pump in mammalian muscle fibers

1988 ◽  
Vol 19 (6) ◽  
pp. 555-559
Author(s):  
A. Kh. Urazaev ◽  
V. A. Surovtsev ◽  
A. V. Chikin ◽  
E. M. Volkov ◽  
G. I. Poletaev ◽  
...  
Keyword(s):  
Muscle Fibers ◽  
Neurotrophic Control ◽  
Mammalian Muscle

The Molecular Diversity of Mammalian Muscle Fibers

Physiology ◽  
1993 ◽  
Vol 8 (4) ◽  
pp. 153-157 ◽  
Author(s):  
D Pette ◽  
RS Staron
Keyword(s):  
Molecular Diversity ◽  
Muscle Fibers ◽  
Protein Isoforms ◽  
Fiber Types ◽  
Mammalian Muscle ◽  
Neural Input ◽  
Multiple Protein ◽  
Isoform Expression ◽  
Dynamic Structures

Although muscle fibers can be separated into major groups, a spectrum of fiber types exists due to the expression of multiple protein isoforms. Also, muscle fibers are dynamic structures with the ability to change isoform expression in response to altered functional demands, changes in neural input, or hormonal signals.

Fast myosin heavy chains expressed in secondary mammalian muscle fibers at the time of their inception

1994 ◽  
Vol 107 (9) ◽  
pp. 2361-2371 ◽  
Author(s):  
M. Cho ◽  
S.M. Hughes ◽  
I. Karsch-Mizrachi ◽  
M. Travis ◽  
L.A. Leinwand ◽  
...  
Keyword(s):  
Muscle Development ◽  
Muscle Fibers ◽  
Fiber Formation ◽  
Mammalian Skeletal Muscle ◽  
Western Blots ◽  
Mammalian Muscle ◽  
Heavy Chains ◽  
Fast Myosin ◽  
Myhc Isoforms ◽  
Fast Myosin Heavy Chain

Mammalian skeletal muscle is generated by two waves of fiber formation, resulting in primary and secondary fibers. These fibers mature to give rise to several classes of adult muscle fibers with distinct contractile properties. Here we describe fast myosin heavy chain (MyHC) isoforms that are expressed in nascent secondary, but not primary, fibers in the early development of rat and human muscle. These fast MyHCs are distinct from previously described embryonic and neonatal fast MyHCs. To identify these MyHCs, monoclonal antibodies were used whose specificity was determined in western blots of MyHCs on denaturing gels and reactivity with muscle tissue at various stages of development. To facilitate a comparison of our results with those of others obtained using different antibodies or species, we have identified cDNAs that encode the epitopes recognized by our antibodies wherever possible. The results suggest that epitopes characteristic of adult fast MyHCs are expressed very early in muscle fiber development and distinguish newly formed secondary fibers from primary fibers. This marker of secondary fibers, which is detectable at the time of their inception, should prove useful in future studies of the derivation of primary and secondary fibers in mammalian muscle development.

scholarly journals An analysis of the relationships between subthreshold electrical properties and excitability in skeletal muscle

2011 ◽  
Vol 138 (1) ◽  
pp. 73-93 ◽  
Author(s):  
Thomas H. Pedersen ◽  
Christopher L.-H. Huang ◽  
James A. Fraser
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Muscle Activity ◽  
Neuromuscular Transmission ◽  
Muscle Fibers ◽  
Low Frequency ◽  
Mammalian Muscle ◽  
Fast Twitch ◽  
T System

Skeletal muscle activation requires action potential (AP) initiation followed by its sarcolemmal propagation and tubular excitation to trigger Ca2+ release and contraction. Recent studies demonstrate that ion channels underlying the resting membrane conductance (GM) of fast-twitch mammalian muscle fibers are highly regulated during muscle activity. Thus, onset of activity reduces GM, whereas prolonged activity can markedly elevate GM. Although these observations implicate GM regulation in control of muscle excitability, classical theoretical studies in un-myelinated axons predict little influence of GM on membrane excitability. However, surface membrane morphologies differ markedly between un-myelinated axons and muscle fibers, predominantly because of the tubular (t)-system of muscle fibers. This study develops a linear circuit model of mammalian muscle fiber and uses this to assess the role of subthreshold electrical properties, including GM changes during muscle activity, for AP initiation, AP propagation, and t-system excitation. Experimental observations of frequency-dependent length constant and membrane-phase properties in fast-twitch rat fibers could only be replicated by models that included t-system luminal resistances. Having quantified these resistances, the resulting models showed enhanced conduction velocity of passive current flow also implicating elevated AP propagation velocity. Furthermore, the resistances filter passive currents such that higher frequency current components would determine sarcolemma AP conduction velocity, whereas lower frequency components excite t-system APs. Because GM modulation affects only the low-frequency membrane impedance, the GM changes in active muscle would predominantly affect neuromuscular transmission and low-frequency t-system excitation while exerting little influence on the high-frequency process of sarcolemmal AP propagation. This physiological role of GM regulation was increased by high Cl− permeability, as in muscle endplate regions, and by increased extracellular [K+], as observed in working muscle. Thus, reduced GM at the onset of exercise would enhance t-system excitation and neuromuscular transmission, whereas elevated GM after sustained activity would inhibit these processes and thereby accentuate muscle fatigue.

Sign in / Sign up

Export Citation Format

Share Document