scholarly journals Acetylcholine receptors and sodium channels in denervated and botulinum-toxin-treated adult rat muscle.

1987 ◽  
Vol 382 (1) ◽  
pp. 69-86 ◽  
Author(s):  
L Bambrick ◽  
T Gordon
Keyword(s):  
Botulinum Toxin ◽  
Sodium Channels ◽  
Acetylcholine Receptors ◽  
Adult Rat ◽  
Rat Muscle

scholarly journals Cytoplasmic actin in postsynaptic structures at the neuromuscular junction.

1981 ◽  
Vol 90 (3) ◽  
pp. 789-792 ◽  
Author(s):  
Z W Hall ◽  
B W Lubit ◽  
J H Schwartz
Keyword(s):  
Neuromuscular Junction ◽  
Mammalian Cells ◽  
Acetylcholine Receptors ◽  
Body Wall ◽  
Neuromuscular Junctions ◽  
Muscle Fibers ◽  
Adult Rat ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
Immunocytochemical Studies

We used an antibody prepared against Aplysia (mollusc) body-wall actin that specifically reacts with certain forms of cytoplasmic actin in mammalian cells to probe for the presence of actin at the neuromuscular junction. Immunocytochemical studies showed that actin or an actinlike molecule is concentrated at neuromuscular junctions of normal and denervated adult rat muscle fibers. Actin is present at the neuromuscular junctions of fibers of developing diaphragm muscles as early as embryonic day 18, well before postsynaptic folds are formed. These results suggest that cytoplasmic actin may play a role in the clustering or stabilization of acetylcholine receptors at the neuromuscular junction.

scholarly journals Topographical segregation of old and new acetylcholine receptors at developing ectopic endplates in adult rat muscle.

1981 ◽  
Vol 88 (1) ◽  
pp. 215-218 ◽  
Author(s):  
C B Weinberg ◽  
C G Reiness ◽  
Z W Hall
Keyword(s):  
Density Distribution ◽  
Soleus Muscle ◽  
Acetylcholine Receptors ◽  
Receptor Cluster ◽  
Visual Impression ◽  
Adult Rat ◽  
Rat Muscle ◽  
Rat Soleus Muscle ◽  
Receptor Clusters ◽  
Alpha Bungarotoxin

We have used radioautographic methods to examine the topography of addition and removal of acetylcholine receptors (AChRs) within receptor clusters at developing ectopic synapses in adult rat soleus muscle. After AChRs within a cluster had been pulse-labeled with 125I-alpha-bungarotoxin (125I-alpha-BuTx), the area that they occupied within the cluster shrank with time. Thus the old receptors at new endplates occupy a continually decreasing area of the growing receptor cluster. To localize newly added AChRs, we pretreated the muscles with unlabeled alpha-BuTx, thus blocking the old receptors, and then labeled newly added receptors with 125I-alpha-BuTx 1 or 2 d later. In radioautographs, AChR clusters from these muscles appeared as annuli or "doughnuts," unlike control (unpretreated) clusters, which were more nearly uniformly labeled. This visual impression was confirmed by analyzing the radial grain density distribution. Thus growth and turnover of AChR clusters at ectopic endplates takes place by the addition of receptors at the periphery of the clusters. Our data are most consistent with a model in which receptor removal occurs by endocytosis randomly throughout the cluster.

scholarly journals β-Spectrin Is Colocalized with Both Voltage-gated Sodium Channels and AnkyrinG at the Adult Rat Neuromuscular Junction

1998 ◽  
Vol 140 (3) ◽  
pp. 675-684 ◽  
Author(s):  
S.J. Wood ◽  
C.R. Slater
Keyword(s):  
Sodium Channels ◽  
Acetylcholine Receptors ◽  
Neuromuscular Junctions ◽  
Local Density ◽  
Cytoskeletal Proteins ◽  
Common Mechanism ◽  
Voltage Gated ◽  
Adult Rat ◽  
Central Neurons ◽  
Voltage Gated Sodium Channels

Voltage-gated sodium channels (VGSCs) are concentrated in the depths of the postsynaptic folds at mammalian neuromuscular junctions (NMJs) where they facilitate action potential generation during neuromuscular transmission. At the nodes of Ranvier and the axon hillocks of central neurons, VGSCs are associated with the cytoskeletal proteins, β-spectrin and ankyrin, which may help to maintain the high local density of VGSCs. Here we show in skeletal muscle, using immunofluorescence, that β-spectrin is precisely colocalized with both VGSCs and ankyrinG, the nodal isoform of ankyrin. In en face views of rat NMJs, acetylcholine receptors (AChRs), and utrophin immunolabeling are organized in distinctive linear arrays corresponding to the crests of the postsynaptic folds. In contrast, β-spectrin, VGSCs, and ankyrinG have a punctate distribution that extends laterally beyond the AChRs, consistent with a localization in the depths of the folds. Double antibody labeling shows that β-spectrin is precisely colocalized with both VGSCs and ankyrinG at the NMJ. Furthermore, quantification of immunofluorescence in labeled transverse sections reveals that β-spectrin is also concentrated in perijunctional regions, in parallel with an increase in labeling of VGSCs and ankyrinG, but not of dystrophin. These observations suggest that interactions with β-spectrin and ankyrinG help to maintain the concentration of VGSCs at the NMJ and that a common mechanism exists throughout the nervous system for clustering VGSCs at a high density.

scholarly journals Structural determinants of channel conductance in fetal and adult rat muscle acetylcholine receptors.

1996 ◽  
Vol 492 (3) ◽  
pp. 775-787 ◽  
Author(s):  
S Herlitze ◽  
A Villarroel ◽  
V Witzemann ◽  
M Koenen ◽  
B Sakmann
Keyword(s):  
Acetylcholine Receptors ◽  
Channel Conductance ◽  
Structural Determinants ◽  
Adult Rat ◽  
Rat Muscle

scholarly journals Association of beta-cytoplasmic actin with high concentrations of acetylcholine receptor (AChR) in normal and anti-AChR-treated primary rat muscle cultures.

1984 ◽  
Vol 32 (9) ◽  
pp. 973-981 ◽  
Author(s):  
B W Lubit
Keyword(s):  
Acetylcholine Receptor ◽  
Acetylcholine Receptors ◽  
Neuromuscular Junctions ◽  
Morphological Changes ◽  
Muscle Cells ◽  
High Concentration ◽  
Rat Muscle ◽  
Cytoplasmic Actin ◽  
High Concentrations

Previous immunocytochemical studies in which an antibody specific for mammalian cytoplasmic actin was used showed that a high concentration of cytoplasmic actin exists at neuromuscular junctions of rat muscle fibers such that the distribution of actin corresponded exactly to that of the acetylcholine receptors. Although clusters of acetylcholine receptors also are present in noninnervated rat and chick muscle cells grown in vitro, neither the mechanism for the formation and maintenance of these clusters nor the relationship of these clusters to the high density of acetylcholine receptors at the neuromuscular junction in vivo are known. In the present study, a relationship between beta-cytoplasmic actin and acetylcholine receptors in vitro has been demonstrated immunocytochemically using an antibody specific for the beta-form of cytoplasmic actin. Networks of cytoplasmic actin-containing filaments were found in discrete regions of the myotube membrane that also contained high concentrations of acetylcholine receptors; such high concentrations of acetylcholine receptors have been described in regions of membrane-substrate contact. Moreover, when primary rat myotubes were exposed to human myasthenic serum, gross morphological changes, accompanied by an apparent rearrangement of the cytoplasmic actin-containing cytoskeleton, were produced. Although whether the distribution of cytoplasmic actin-containing structures was influenced by the organization of acetylcholine receptor or vice versa cannot be determined from these studies, these findings suggest that in primary rat muscle cells grown in vitro, acetylcholine receptors and beta-cytoplasmic actin-containing structures may be somehow connected.

Sign in / Sign up

Export Citation Format

Share Document