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Isoform-specific Na,K-ATPase alterations precede disuse-induced atrophy of rat soleus muscle.

Kravtsova VV, Matchkov VV, Bouzinova EV, Vasiliev AN, Razgovorova IA, Heiny JA, Krivoi II - Biomed Res Int (2015)

Bottom Line: Our results indicate that 24-72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers.This decrease occurs prior to muscle atrophy or any change in contractile parameters.The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change.

View Article: PubMed Central - PubMed

Affiliation: St. Petersburg State University, 7/9 University emb., St. Petersburg 199034, Russia.

ABSTRACT
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 the α1 and α2 Na,K-ATPase; the functional activity and plasma membrane localization of the α2 Na,K-ATPase. Our results indicate that 24-72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers. This decrease occurs prior to muscle atrophy or any change in contractile parameters. The α2 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 restore α2 enzyme activity in the disused soleus muscle. There was no change in the membrane localization of α2 Na,K-ATPase. The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change. Our findings suggest that skeletal muscle use is absolutely required for α2 Na,K-ATPase transport activity and provide the first evidence that Na,K-ATPase alterations precede HS-induced muscle atrophy.

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Related in: MedlinePlus

Effects of 24–72 h of hindlimb suspension on body and muscle weights (a), muscle-to-body weight ratio (b), and parameters (c) of rat soleus twitch tensions. *P < 0.05; **P < 0.01 compared to control.
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fig1: Effects of 24–72 h of hindlimb suspension on body and muscle weights (a), muscle-to-body weight ratio (b), and parameters (c) of rat soleus twitch tensions. *P < 0.05; **P < 0.01 compared to control.

Mentions: The body and soleus muscle weights of control rats were 209.8 ± 6.5 g (40 rats) and 127.3 ± 6.4 mg (40 pairs of muscles), respectively. The body weight was not changed during HS while the soleus muscle weight significantly (P < 0.01) decreased to 96.0 ± 5.9 mg (22 pairs of muscles) (Figure 1(a)). As a useful index of muscle atrophy, we determined changes of the muscle mass expressed as soleus muscle weight (mg) normalized to the whole body weight (g). In control soleus muscle the muscle-to-body weight ratio was 0.60 ± 0.02 mg/g (40 rats, 40 pairs of muscles) similar to published values [29]. Only a slight and non-significant decrease of this ratio was observed after 24 h of HS. However this ratio significantly (P < 0.01) decreased to 0.47 ± 0.02 mg/g (22 rats, 22 pairs of muscles) after 72 h of HS (Figure 1(b)), corresponding well with the 11% decrease in mean cross sectional area of individual soleus muscle fibers (from 1687 ± 22 μm2, 502 fibers, in control down to 1511 ± 21 μm2, 475 fibers, after HS, P < 0.01). Mean cross sectional area after 24 h of HS was not determined.


Isoform-specific Na,K-ATPase alterations precede disuse-induced atrophy of rat soleus muscle.

Kravtsova VV, Matchkov VV, Bouzinova EV, Vasiliev AN, Razgovorova IA, Heiny JA, Krivoi II - Biomed Res Int (2015)

Effects of 24–72 h of hindlimb suspension on body and muscle weights (a), muscle-to-body weight ratio (b), and parameters (c) of rat soleus twitch tensions. *P < 0.05; **P < 0.01 compared to control.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4309216&req=5

fig1: Effects of 24–72 h of hindlimb suspension on body and muscle weights (a), muscle-to-body weight ratio (b), and parameters (c) of rat soleus twitch tensions. *P < 0.05; **P < 0.01 compared to control.
Mentions: The body and soleus muscle weights of control rats were 209.8 ± 6.5 g (40 rats) and 127.3 ± 6.4 mg (40 pairs of muscles), respectively. The body weight was not changed during HS while the soleus muscle weight significantly (P < 0.01) decreased to 96.0 ± 5.9 mg (22 pairs of muscles) (Figure 1(a)). As a useful index of muscle atrophy, we determined changes of the muscle mass expressed as soleus muscle weight (mg) normalized to the whole body weight (g). In control soleus muscle the muscle-to-body weight ratio was 0.60 ± 0.02 mg/g (40 rats, 40 pairs of muscles) similar to published values [29]. Only a slight and non-significant decrease of this ratio was observed after 24 h of HS. However this ratio significantly (P < 0.01) decreased to 0.47 ± 0.02 mg/g (22 rats, 22 pairs of muscles) after 72 h of HS (Figure 1(b)), corresponding well with the 11% decrease in mean cross sectional area of individual soleus muscle fibers (from 1687 ± 22 μm2, 502 fibers, in control down to 1511 ± 21 μm2, 475 fibers, after HS, P < 0.01). Mean cross sectional area after 24 h of HS was not determined.

Bottom Line: Our results indicate that 24-72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers.This decrease occurs prior to muscle atrophy or any change in contractile parameters.The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change.

View Article: PubMed Central - PubMed

Affiliation: St. Petersburg State University, 7/9 University emb., St. Petersburg 199034, Russia.

ABSTRACT
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 the α1 and α2 Na,K-ATPase; the functional activity and plasma membrane localization of the α2 Na,K-ATPase. Our results indicate that 24-72 h of HS specifically decreases the electrogenic activity of the Na,K-ATPase α2 isozyme and the RMP of soleus muscle fibers. This decrease occurs prior to muscle atrophy or any change in contractile parameters. The α2 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 restore α2 enzyme activity in the disused soleus muscle. There was no change in the membrane localization of α2 Na,K-ATPase. The α1 Na,K-ATPase electrogenic activity, protein and mRNA content did not change. Our findings suggest that skeletal muscle use is absolutely required for α2 Na,K-ATPase transport activity and provide the first evidence that Na,K-ATPase alterations precede HS-induced muscle atrophy.

Show MeSH
Related in: MedlinePlus