Denervated skeletal muscle fibers develop discrete patches of high acetylcholine receptor density

Science ◽  
1977 ◽  
Vol 196 (4289) ◽  
pp. 540-542 ◽  
Author(s):  
P. Ko ◽  
M. Anderson ◽  
M. Cohen
Keyword(s):  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Muscle Fibers ◽  
Receptor Density ◽  
Skeletal Muscle Fibers ◽  
Acetylcholine Receptor Density

Acetylcholine Receptor Density and Acetylcholinesterase Activity in Skeletal Muscle of Rats Following Thermal Injury

1989 ◽  
Vol 70 (4) ◽  
pp. 654-659 ◽  
Author(s):  
Punit H. Marathe ◽  
Richard H. Haschke ◽  
John T. Slattery ◽  
Jonathan R. Zucker ◽  
Edward G. Pavlin
Keyword(s):  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Thermal Injury ◽  
Acetylcholinesterase Activity ◽  
Receptor Density ◽  
Acetylcholine Receptor Density

scholarly journals Defective Acetylcholine Receptor Subunit Switch Precedes Atrophy of Slow-Twitch Skeletal Muscle Fibers Lacking ERK1/2 Kinases in Soleus Muscle

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Shuo Wang ◽  
Bonnie Seaberg ◽  
Ximena Paez-Colasante ◽  
Mendell Rimer
Keyword(s):  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Soleus Muscle ◽  
Muscle Fibers ◽  
Neuromuscular Synapse ◽  
Fiber Morphology ◽  
Skeletal Muscle Fibers ◽  
Slow Twitch

Abstract To test the role of extracellular-signal regulated kinases 1 and 2 (ERK1/2) in slow-twitch, type 1 skeletal muscle fibers, we studied the soleus muscle in mice genetically deficient for myofiber ERK1/2. Young adult mutant soleus was drastically wasted, with highly atrophied type 1 fibers, denervation at most synaptic sites, induction of “fetal” acetylcholine receptor gamma subunit (AChRγ), reduction of “adult” AChRε, and impaired mitochondrial biogenesis and function. In weanlings, fiber morphology and mitochondrial markers were mostly normal, yet AChRγ upregulation and AChRε downregulation were observed. Synaptic sites with fetal AChRs in weanling muscle were ~3% in control and ~40% in mutants, with most of the latter on type 1 fibers. These results suggest that: (1) ERK1/2 are critical for slow-twitch fiber growth; (2) a defective γ/ε-AChR subunit switch, preferentially at synapses on slow fibers, precedes wasting of mutant soleus; (3) denervation is likely to drive this wasting, and (4) the neuromuscular synapse is a primary subcellular target for muscle ERK1/2 function in vivo.

scholarly journals Repression of slow myosin heavy chain 2 gene expression in fast skeletal muscle fibers by muscarinic acetylcholine receptor and Gαq signaling

2003 ◽  
Vol 162 (5) ◽  
pp. 843-850 ◽  
Author(s):  
Theresa Jordan ◽  
Jinyuan Li ◽  
Hongbin Jiang ◽  
Joseph X. DiMario
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Muscle Fibers ◽  
Muscarinic Acetylcholine Receptor ◽  
Fast Skeletal Muscle ◽  
Muscarinic Acetylcholine ◽  
Fiber Properties ◽  
Skeletal Muscle Fibers ◽  
Slow Myosin Heavy Chain

Gene expression in skeletal muscle fibers is regulated by innervation and intrinsic fiber properties. To determine the mechanism of repression of slow MyHC2 expression in innervated fast pectoralis major (PM) fibers, we investigated the function of the muscarinic acetylcholine receptor (mAchR) and Gαq. Both mAchR and Gαq are abundant in medial adductor (MA) and PM fibers, and mAchR and Gαq interact in these fibers. Whereas innervation of PM fibers was insufficient to induce slow MyHC2 expression, inhibition of mAchR activity with atropine in innervated PM fibers induced slow MyHC2 expression. Increased Gαq activity repressed slow MyHC2 expression to nondetectable levels in innervated MA fibers. Reduced mAchR activity decreased PKC activity in PM fibers, and increased Gαq activity increased PKC activity in PM and MA fibers. Decreased PKC activity in atropine-treated innervated PM fibers correlated with slow MyHC2 expression. These data suggest that slow MyHC2 repression in innervated fast PM fibers is mediated by cell signaling involving mAchRs, Gαq, and PKC.

scholarly journals Muscle Activity and Muscle Agrin Regulate the Organization of Cytoskeletal Proteins and Attached Acetylcholine Receptor (Achr) Aggregates in Skeletal Muscle Fibers

2001 ◽  
Vol 153 (7) ◽  
pp. 1453-1464 ◽  
Author(s):  
Gabriela Bezakova ◽  
Terje Lømo
Keyword(s):  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Muscle Activity ◽  
Muscle Fibers ◽  
Cytoskeletal Proteins ◽  
Transverse Orientation ◽  
Single Application ◽  
Skeletal Muscle Fibers ◽  
Denervated Muscles ◽  
Electrical Muscle

In innervated skeletal muscle fibers, dystrophin and β-dystroglycan form rib-like structures (costameres) that appear as predominantly transverse stripes over Z and M lines. Here, we show that the orientation of these stripes becomes longitudinal in denervated muscles and transverse again in denervated electrically stimulated muscles. Skeletal muscle fibers express nonneural (muscle) agrin whose function is not well understood. In this work, a single application of ≥10 nM purified recombinant muscle agrin into denervated muscles preserved the transverse orientation of costameric proteins that is typical for innervated muscles, as did a single application of ≥1 μM neural agrin. At lower concentration, neural agrin induced acetylcholine receptor aggregates, which colocalized with longitudinally oriented β-dystroglycan, dystrophin, utrophin, syntrophin, rapsyn, and β2-laminin in denervated unstimulated fibers and with the same but transversely oriented proteins in innervated or denervated stimulated fibers. The results indicate that costameres are plastic structures whose organization depends on electrical muscle activity and/or muscle agrin.

scholarly journals Neural agrin controls acetylcholine receptor stability in skeletal muscle fibers

2001 ◽  
Vol 98 (17) ◽  
pp. 9924-9929 ◽  
Author(s):  
G. Bezakova ◽  
I. Rabben ◽  
I. Sefland ◽  
G. Fumagalli ◽  
T. Lomo
Keyword(s):  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Muscle Fibers ◽  
Skeletal Muscle Fibers

The “KIMWIPE” Effect in Ultra-Thin Cryosections

1985 ◽  
Vol 43 ◽  
pp. 458-459
Author(s):  
I. Taylor ◽  
P. Ingram ◽  
J.R. Sommer
Keyword(s):  
Skeletal Muscle ◽  
Electrical Stimulation ◽  
Muscle Fibers ◽  
Ice Crystals ◽  
Crystal Formation ◽  
Ice Crystal ◽  
Thin Sections ◽  
Skeletal Muscle Fibers ◽  
Freeze Dried ◽  
Ice Crystal Formation

In studying quick-frozen single intact skeletal muscle fibers for structural and microchemical alterations that occur milliseconds, and fractions thereof, after electrical stimulation, we have developed a method to compare, directly, ice crystal formation in freeze-substituted thin sections adjacent to all, and beneath the last, freeze-dried cryosections. We have observed images in the cryosections that to our knowledge have not been published heretofore (Figs.1-4). The main features are that isolated, sometimes large regions of the sections appear hazy and have much less contrast than adjacent regions. Sometimes within the hazy regions there are smaller areas that appear crinkled and have much more contrast. We have also observed that while the hazy areas remain still, the regions of higher contrast visibly contract in the beam, often causing tears in the sections that are clearly not caused by ice crystals (Fig.3, arrows).

Effect of External Calcium and other Divalent Cations on K+ Contractures in Denervated Slow Skeletal Muscle Fibers of the Frog

2019 ◽  
Author(s):  
Leonardo Hernández
Keyword(s):  
Skeletal Muscle ◽  
Binding Capacity ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Free Calcium ◽  
Slow Skeletal Muscle ◽  
Skeletal Muscle Fibers ◽  
Free Calcium Concentration ◽  
Chronic Denervation ◽  
Denervated Muscles

The influence of Ca2+ and other divalent cations on contractile responses of slow skeletal muscle fibers of the frog (Rana pipiens) under conditions of chronic denervation was investigated.Isometric tension was recorded from slow bundles of normal and denervated cruralis muscle in normal solution and in solutions with free calcium concentration solution or in solutions where other divalent cations (Sr2+, Ni2+, Co2+ or Mn2+) substituted for calcium. In the second week after nerve section, in Ca2+-free solutions, we observed that contractures (evoked from 40 to 80 mM-K+) of non-denervated muscles showed significantly higher tensions (p<0.05), than those from denervated bundles. Likewise, in solutions where calcium was substituted by all divalent cations tested, with exception of Mn2+, the denervated bundles displayed lower tension than non-denervated, also in the second week of denervation. In this case, the Ca2+ substitution by Sr2+ caused the higher decrease in tension, followed by Co2+ and Ni2+, which were different to non-denervated bundles, as the lowest tension was developed by Mn2+, followed by Co2+, and then Ni2+ and Sr2+. After the third week, we observed a recovery in tension. These results suggest that denervation altering the binding capacity to divalent cations of the voltage sensor.

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