THE PERMEABILITY OF THE BASAL LAMINA AT THE NEUROMUSCULAR JUNCTION. AN ULTRASTRUCTURAL STUDY OF RAT SKELETAL MUSCLE USING PARTICULATE TRACERS

1983 ◽  
Vol 9 (6) ◽  
pp. 419-432 ◽  
Author(s):  
A. OLDFORS ◽  
M. FARDEAU
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Basal Lamina ◽  
Ultrastructural Study ◽  
Rat Skeletal Muscle

scholarly journals Concentration of Caveolin-3 at the Neuromuscular Junction in Young and Old Rat Skeletal Muscle Fibers

2003 ◽  
Vol 51 (9) ◽  
pp. 1113-1118 ◽  
Author(s):  
Bruce M. Carlson ◽  
Jean A. Carlson ◽  
Eduard I. Dedkov ◽  
Ian S. McLennan
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Muscle Fibers ◽  
Normal Aging ◽  
Rat Skeletal Muscle ◽  
Phenotypic Characteristics ◽  
Adult Rat ◽  
Rat Muscle ◽  
Functional Implications ◽  
Old Rats

Caveolin-3, a muscle-specific member of the caveolin family, is strongly localized to the neuromuscular junction (NMJ) in adult rat muscle fibers, where it co-localizes with α-bungarotoxin staining. In 24-month-old rats, less distinct staining corresponds with the normal aging changes in the NMJ. After denervation, the pattern and intensity of staining begin to break up as early as 3 days, and by 10 days little staining remains. The functional implications of this concentration of caveolin-3 at the NMJ remain obscure, but it is possible that its absence could account for some of the phenotypic characteristics of individuals with caveolin-3 mutations.

scholarly journals Metabolic stabilization of acetylcholine receptors in vertebrate neuromuscular junction by muscle activity.

1990 ◽  
Vol 111 (2) ◽  
pp. 655-661 ◽  
Author(s):  
S Rotzler ◽  
H R Brenner
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Muscle Activity ◽  
Acetylcholine Receptors ◽  
Muscle Stimulation ◽  
Cluster Growth ◽  
Rat Skeletal Muscle ◽  
Achr Cluster ◽  
End Plate ◽  
Alpha Bungarotoxin

The effects of muscle activity on the growth of synaptic acetylcholine receptor (AChR) accumulations and on the metabolic AChR stability were investigated in rat skeletal muscle. Ectopic end plates induced surgically in adult soleus muscle were denervated early during development when junctional AChR number and stability were still low and, subsequently, muscles were either left inactive or they were kept active by chronic exogenous stimulation. AChR numbers per ectopic AChR cluster and AChR stabilities were estimated from the radioactivity and its decay with time, respectively, of end plate sites whose AChRs had been labeled with 125I-alpha-bungarotoxin (alpha-butx). The results show that the metabolic stability of the AChRs in ectopic clusters is reversibly increased by muscle activity even when innervation is eliminated very early in development. 1 d of stimulation is sufficient to stabilize the AChRs in ectopic AChR clusters. Muscle stimulation also produced an increase in the number of AChRs at early denervated end plates. Activity-induced cluster growth occurs mainly by an increase in area rather than in AChR density, and for at least 10 d after denervation is comparable to that in normally developing ectopic end plates. The possible involvement of AChR stabilization in end plate growth is discussed.

scholarly journals Laminin, fibronectin, and collagen in synaptic and extrasynaptic portions of muscle fiber basement membrane.

1982 ◽  
Vol 93 (2) ◽  
pp. 442-451 ◽  
Author(s):  
J R Sanes
Keyword(s):  
Skeletal Muscle ◽  
Electron Microscope ◽  
Basement Membrane ◽  
Basal Lamina ◽  
Muscle Fiber ◽  
Synaptic Cleft ◽  
Neuromuscular Function ◽  
Collagen Iv ◽  
Rat Skeletal Muscle ◽  
Immunohistochemical Methods

Light and electron microscope immunohistochemical methods were used to study the distribution of several proteins in rat skeletal muscle. The aims were to identify components of muscle fiber basement membrane and to compare the small fraction (0.1%) of the basement membrane that extends through the synaptic cleft at the neuromuscular junction with the remaining, extrasynaptic portion. Synaptic basement membrane is functionally specialized and plays important roles in neuromuscular function and regeneration. Laminin, fibronectin, collagen IV, collagen V, and a collagenous protein (high-salt-soluble protein [HSP]) are all present in muscle fiber basement membrane. Laminin and collagen IV are concentrated in basal lamina (the feltlike, inner layer of the basement membrane) and are shared by synaptic and extrasynaptic regions. Fibronectin, also present synaptically and extrasynaptically, is present in basal lamina and in the overlying reticular lamina. Collagen V and HSP are present throughout extrasynaptic basement membrane but are absent from synaptic sites; HSP is concentrated in the reticular lamina and on the outer surface of the basal lamina. These results, together with experiments reported previously (Sanes and Hall, 1979. J. Cell Biol: 83:357--370), provide examples of three classes of components in muscle fiber basement membrane--synaptic, extrasynaptic, and shared.

scholarly journals Aggregates of acetylcholine receptors are associated with plaques of a basal lamina heparan sulfate proteoglycan on the surface of skeletal muscle fibers.

1983 ◽  
Vol 97 (5) ◽  
pp. 1396-1411 ◽  
Author(s):  
M J Anderson ◽  
D M Fambrough
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Heparan Sulfate ◽  
Basal Lamina ◽  
Acetylcholine Receptors ◽  
Muscle Fibers ◽  
Muscle Cells ◽  
Heparan Sulfate Proteoglycan ◽  
Sulfate Proteoglycan ◽  
Skeletal Muscle Fibers

Hybridoma techniques have been used to generate monoclonal antibodies to an antigen concentrated in the basal lamina at the Xenopus laevis neuromuscular junction. The antibodies selectively precipitate a high molecular weight heparan sulfate proteoglycan from conditioned medium of muscle cultures grown in the presence of [35S]methionine or [35S]sulfate. Electron microscope autoradiography of adult X. laevis muscle fibers exposed to 125I-labeled antibody confirms that the antigen is localized within the basal lamina of skeletal muscle fibers and is concentrated at least fivefold within the specialized basal lamina at the neuromuscular junction. Fluorescence immunocytochemical experiments suggest that a similar proteoglycan is also present in other basement membranes, including those associated with blood vessels, myelinated axons, nerve sheath, and notochord. During development in culture, the surface of embryonic muscle cells displays a conspicuously non-uniform distribution of this basal lamina proteoglycan, consisting of large areas with a low antigen site-density and a variety of discrete plaques and fibrils. Clusters of acetylcholine receptors that form on muscle cells cultured without nerve are invariably associated with adjacent, congruent plaques containing basal lamina proteoglycan. This is also true for clusters of junctional receptors formed during synaptogenesis in vitro. This correlation indicates that the spatial organization of receptor and proteoglycan is coordinately regulated, and suggests that interactions between these two species may contribute to the localization of acetylcholine receptors at the neuromuscular junction.

scholarly journals Antibodies that bind specifically to synaptic sites on muscle fiber basal lamina.

1979 ◽  
Vol 83 (2) ◽  
pp. 357-370 ◽  
Author(s):  
J R Sanes ◽  
Z W Hall
Keyword(s):  
Skeletal Muscle ◽  
Neuromuscular Junction ◽  
Basal Lamina ◽  
Muscle Fiber ◽  
Differential Susceptibility ◽  
Synaptic Cleft ◽  
Lens Capsule ◽  
Anterior Lens Capsule ◽  
Basement Membrane Collagen ◽  
Immunohistochemical Techniques

Basal lamina (BL) ensheathes each skeletal muscle fiber and passes through the synaptic cleft at the neuromuscular junction. Synaptic portions of the BL are known to play important roles in the formation, function, and maintenance of the neuromuscular junction. Here we demonstrate molecular differences between synaptic and extrasynaptic BL. We obtained antisera to immunogens that might be derived from or share determinants with muscle fiber BL, and used immunohistochemical techniques to study the binding of antibodies to rat skeletal muscle. Four antisera contained antibodies that distinguished synaptic from extrasynaptic portions of the muscle fiber's surface. They were anti-anterior lens capsule, anti-acetylcholinesterase, anti-lens capsule collagen, and anti-muscle basement membrane collagen; the last two sera were selective only after antibodies binding to extrasynaptic areas had been removed by adsorption with connective tissue from endplate-free regions of muscle. Synaptic antigens revealed by each of the four sera were present on the external cell surface and persisted after removal of nerve terminal. Schwann cell, and postsynaptic plasma membrane. Thus, the antigens are contained in or connected to BL of the synaptic cleft. Details of staining patterns, differential susceptibility of antigens to proteolysis, and adsorption experiments showed that the antibodies define at least three different determinants that are present in synaptic but not extrasynaptic BL.

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