scholarly journals Distinct α2 Na,K-ATPase membrane pools are differently involved in early skeletal muscle remodeling during disuse

2016 ◽  
Vol 147 (2) ◽  
pp. 175-188 ◽  
Author(s):  
Violetta V. Kravtsova ◽  
Alexey M. Petrov ◽  
Vladimir V. Matchkov ◽  
Elena V. Bouzinova ◽  
Alexander N. Vasiliev ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Skeletal Muscles ◽  
Contractile Function ◽  
Hindlimb Suspension ◽  
Resting Membrane Potential ◽  
Mrna Content ◽  
Rat Soleus Muscle

The Na,K-ATPase is essential for the contractile function of skeletal muscle, which expresses the α1 and α2 subunit isoforms of Na,K-ATPase. The α2 isozyme is predominant in adult skeletal muscles and makes a greater contribution in working compared with noncontracting muscles. Hindlimb suspension (HS) is a widely used model of muscle disuse that leads to progressive atrophy of postural skeletal muscles. This study examines the consequences of acute (6–12 h) HS on the functioning of the Na,K-ATPase α1 and α2 isozymes in rat soleus (disused) and diaphragm (contracting) muscles. Acute disuse dynamically and isoform-specifically regulates the electrogenic activity, protein, and mRNA content of Na,K-ATPase α2 isozyme in rat soleus muscle. Earlier disuse-induced remodeling events also include phospholemman phosphorylation as well as its increased abundance and association with α2 Na,K-ATPase. The loss of α2 Na,K-ATPase activity results in reduced electrogenic pump transport and depolarized resting membrane potential. The decreased α2 Na,K-ATPase activity is caused by a decrease in enzyme activity rather than by altered protein and mRNA content, localization in the sarcolemma, or functional interaction with the nicotinic acetylcholine receptors. The loss of extrajunctional α2 Na,K-ATPase activity depends strongly on muscle use, and even the increased protein and mRNA content as well as enhanced α2 Na,K-ATPase abundance at this membrane region after 12 h of HS cannot counteract this sustained inhibition. In contrast, additional factors may regulate the subset of junctional α2 Na,K-ATPase pool that is able to recover during HS. Notably, acute, low-intensity muscle workload restores functioning of both α2 Na,K-ATPase pools. These results demonstrate that the α2 Na,K-ATPase in rat skeletal muscle is dynamically and acutely regulated by muscle use and provide the first evidence that the junctional and extrajunctional pools of the α2 Na,K-ATPase are regulated differently.

scholarly journals Isoform-Specific Na,K-ATPase Alterations Precede Disuse-Induced Atrophy of Rat Soleus Muscle

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Violetta V. Kravtsova ◽  
Vladimir V. Matchkov ◽  
Elena V. Bouzinova ◽  
Alexander N. Vasiliev ◽  
Irina A. Razgovorova ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Soleus Muscle ◽  
Muscle Fibers ◽  
Hindlimb Suspension ◽  
Resting Membrane Potential ◽  
Membrane Localization ◽  
Specific Effects ◽  
Contractile Parameters ◽  
Mrna Content ◽  
Rat Soleus Muscle

This study examines the isoform-specific effects of short-term hindlimb suspension (HS) on the Na,K-ATPase in rat soleus muscle. Rats were exposed to 24–72 h of HS and we analyzed the consequences on soleus muscle mass and contractile parameters; excitability and the resting membrane potential (RMP) of muscle fibers; the electrogenic activity, protein, and mRNA content of theα1 andα2 Na,K-ATPase; the functional activity and plasma membrane localization of theα2 Na,K-ATPase. Our results indicate that 24–72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPaseα2 isozyme and the RMP of soleus muscle fibers. This decrease occurs prior to muscle atrophy or any change in contractile parameters. Theα2 mRNA and protein content increased after 24 h of HS and returned to initial levels at 72 h; however, even the increased content was not able to restoreα2 enzyme activity in the disused soleus muscle. There was no change in the membrane localization ofα2 Na,K-ATPase. Theα1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change. Our findings suggest that skeletal muscle use is absolutely required forα2 Na,K-ATPase transport activity and provide the first evidence that Na,K-ATPase alterations precede HS-induced muscle atrophy.

scholarly journals Chronic Ouabain Prevents Na,K-ATPase Dysfunction and Targets AMPK and IL-6 in Disused Rat Soleus Muscle

2021 ◽  
Vol 22 (8) ◽  
pp. 3920
Author(s):  
Violetta V. Kravtsova ◽  
Inna I. Paramonova ◽  
Natalia A. Vilchinskaya ◽  
Maria V. Tishkova ◽  
Vladimir V. Matchkov ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Single Injection ◽  
Chronic Administration ◽  
Motor Dysfunction ◽  
Hindlimb Suspension ◽  
Muscle Disuse ◽  
Rat Soleus Muscle ◽  
Amp Activated Protein Kinase ◽  
Specific Ligand

Sustained sarcolemma depolarization due to loss of the Na,K-ATPase function is characteristic for skeletal muscle motor dysfunction. Ouabain, a specific ligand of the Na,K-ATPase, has a circulating endogenous analogue. We hypothesized that the Na,K-ATPase targeted by the elevated level of circulating ouabain modulates skeletal muscle electrogenesis and prevents its disuse-induced disturbances. Isolated soleus muscles from rats intraperitoneally injected with ouabain alone or subsequently exposed to muscle disuse by 6-h hindlimb suspension (HS) were studied. Conventional electrophysiology, Western blotting, and confocal microscopy with cytochemistry were used. Acutely applied 10 nM ouabain hyperpolarized the membrane. However, a single injection of ouabain (1 µg/kg) prior HS was unable to prevent the HS-induced membrane depolarization. Chronic administration of ouabain for four days did not change the α1 and α2 Na,K-ATPase protein content, however it partially prevented the HS-induced loss of the Na,K-ATPase electrogenic activity and sarcolemma depolarization. These changes were associated with increased phosphorylation levels of AMP-activated protein kinase (AMPK), its substrate acetyl-CoA carboxylase and p70 protein, accompanied with increased mRNA expression of interleikin-6 (IL-6) and IL-6 receptor. Considering the role of AMPK in regulation of the Na,K-ATPase, we suggest an IL-6/AMPK contribution to prevent the effects of chronic ouabain under skeletal muscle disuse.

A novel alpha conotoxin (α-PIB) isolated from C. purpurascens is selective for skeletal muscle nicotinic acetylcholine receptors

Toxicon ◽  
2007 ◽  
Vol 49 (8) ◽  
pp. 1193-1199 ◽  
Author(s):  
Estuardo López-Vera ◽  
Richard B. Jacobsen ◽  
Michael Ellison ◽  
Baldomero M. Olivera ◽  
Russell W. Teichert
Keyword(s):  
Skeletal Muscle ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Nicotinic Acetylcholine

Altered contractile proteins in skeletal muscle of diabetic rats

1987 ◽  
Vol 253 (4) ◽  
pp. E395-E400 ◽  
Author(s):  
P. K. Ganguly ◽  
Y. Taira ◽  
V. Elimban ◽  
M. Roy ◽  
N. S. Dhalla
Keyword(s):  
Skeletal Muscle ◽  
Atpase Activity ◽  
Gel Electrophoresis ◽  
Contractile Function ◽  
Sodium Dodecyl ◽  
Contractile Proteins ◽  
Diabetic Rats ◽  
Hindlimb Muscle ◽  
Myosin Isozyme ◽  
Muscle Myosin

The ATPase activity of myofibrils and myosin from hindlimb muscle was investigated in animals 4 wk after the induction of diabetes by an intravenous injection of streptozotocin (65 mg/kg). Ca2+-stimulated ATPase in myofibrils was increased in diabetic muscle at various times of incubation (1-7 min) as well as at different concentrations of free Ca2+ (10(-7)-10(-5) M Ca2+). Such an increase in Ca2+-stimulated ATPase was evident as early as 1 wk after streptozotocin injection, but Mg2+-ATPase activity remained unaltered. Treatment of diabetic animals with insulin Ca2+-ATPase and actin-activated ATPase activities of pure myosin were similarly increased in diabetic muscle. Myosin ATPase was also activated by K+- or NH4+-EDTA; these responses were more in diabetic muscle. However, sodium dodecyl sulfate gel electrophoresis failed to reveal differences in the patterns of contractile proteins, and pyrophosphate gels did not show significant changes in myosin isozyme patterns between diabetics and controls. The results of this study demonstrate an activation of contractile protein ATPase of skeletal muscle in diabetes and seem to indicate that such an alteration may be responsible for enhanced contractile function of skeletal muscle in this disease.

scholarly journals Thymic B lymphocyte clones from patients with myasthenia gravis secrete monoclonal striational autoantibodies reacting with myosin, alpha actinin, or actin.

1986 ◽  
Vol 164 (4) ◽  
pp. 1043-1059 ◽  
Author(s):  
C L Williams ◽  
V A Lennon
Keyword(s):  
Skeletal Muscle ◽  
Epithelial Cells ◽  
Myasthenia Gravis ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
B Lymphocyte ◽  
High Yield ◽  
Thymic Epithelial Cells ◽  
Anchoring Proteins ◽  
Mucosal Cells

Striational autoantibodies (StrAb), which react with elements of skeletal muscle cross-striations, occur frequently in patients with thymoma associated with myasthenia gravis (MG). Dissociated thymic lymphocytes from 22 of 72 MG patients secreted StrAb when cultured with PWM. A high yield of EBV-transformed B cell lines was established from thymus, thymoma, and peripheral blood of seven patients with MG, but clones secreting StrAb arose only from the three patients who had StrAb in their sera. The monoclonal StrAb bound to A bands or I bands in skeletal muscle of human, rat, and frog. One bound to mitochondria in addition to myofibrillar I bands. None bound to nuclei, smooth muscle, or gastric mucosal cells. In immunoblot analyses and ELISAs the monoclonal StrAb bound to muscle and nonmuscle isotypes of myosin, alpha actinin, and/or actin. All bound to contractile proteins common to thymus and muscle, and one selectively immunostained epithelial cells of the thymic medulla. From these antigenic specificities we suggest that StrAb might arise as an immune response directed against the cytoskeletal anchoring proteins associated with nicotinic acetylcholine receptors in thymic epithelial cells undergoing neoplastic transformation to thymoma.

Age effect on expression of myosin heavy and light chain isoforms in suspended rat soleus muscle

1999 ◽  
Vol 86 (5) ◽  
pp. 1483-1489 ◽  
Author(s):  
Ayako Saitoh ◽  
Tadashi Okumoto ◽  
Hiroshi Nakano ◽  
Masanobu Wada ◽  
Shigeru Katsuta
Keyword(s):  
Light Chain ◽  
Differential Effect ◽  
Skeletal Muscles ◽  
Age Effect ◽  
Hindlimb Suspension ◽  
Adult Rats ◽  
Age Dependent ◽  
Rat Soleus Muscle ◽  
Old Rats ◽  
Fast Twitch

This study was designed to test the hypothesis that myosin heavy (MHC) and light chain (MLC) plasticity resulting from hindlimb suspension (HS) is an age-dependent process. By using an electrophoretic technique, the distribution of MHC and MLC isoforms was quantitatively evaluated in the soleus muscles from 3- or 12-wk-old rats after 1–3 wk of HS treatment was maintained. In normal 12- and 15-wk-old rats, the soleus muscles contained a predominance of MHCI (∼94%) with small amounts of MHCIIa, but not MHCIId or MHCIIb. The suspended muscles of adult rats were characterized by the appearance of MHCIIb and MHCIId, the latter reaching ∼6% after 3 wk of HS treatment. In contrast to changes in MHC, HS did not induce a transition in the MLC pattern in the soleus muscles from adult rats. Compared with adult rats, in juveniles HS had a much more pronounced effect on the shift toward faster MHC and MLC isoform expression. The soleus muscles of 6-wk-old rats after 3 wk of HS were composed of 37.0% MHCI, 19.1% MHCIIa, 23.7% MHCIId, and 20.2% MHCIIb. Changes in MLC isoforms consisted of an increase in MLC1fand MLC2f concomitant with a decrease in MLC2s. These results indicate the existence of a differential effect of HS on MHC and MLC transitions that appears to be age dependent. They also suggest that the suspended soleus muscles from young rats may acquire the intrinsic contractile properties that are intermediate between those in the normal soleus and typical fast-twitch skeletal muscles.

Infraterminal spreading and extrajunctional expression of nicotinic acetylcholine receptors in denervated rat skeletal muscle

1999 ◽  
Vol 125 (4) ◽  
pp. 426-434 ◽  
Author(s):  
Bertalan Csillik ◽  
János Nemcsók ◽  
Bruce Chase ◽  
Anita E. Csillik ◽  
Elizabeth Knyihár-Csillik
Keyword(s):  
Skeletal Muscle ◽  
Nicotinic Acetylcholine Receptors ◽  
Acetylcholine Receptors ◽  
Rat Skeletal Muscle ◽  
Nicotinic Acetylcholine
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