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Neuronal nitric oxide synthase is dislocated in type I fibers of myalgic muscle but can recover with physical exercise training.

Jensen L, Andersen LL, Schrøder HD, Frandsen U, Sjøgaard G - Biomed Res Int (2015)

Bottom Line: Distribution of fiber type, cross-sectional area, and sarcolemmal nNOS expression did not differ between MYA and CON.However, MYA showed increased sarcoplasmic nNOS localization (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) compared with CON.SST resulted in a decrease of sarcoplasm-localized nNOS following training (before 18.1 ± 12 versus after 12.0 ± 12%; P = 0,027).

View Article: PubMed Central - PubMed

Affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, 5000 Odense C, Denmark ; Institute of Clinical Research, Pathology and SDU Muscle Research Cluster, University of Southern Denmark, 5230 Odense M, Denmark.

ABSTRACT
Trapezius myalgia is the most common type of chronic neck pain. While physical exercise reduces pain and improves muscle function, the underlying mechanisms remain unclear. Nitric oxide (NO) signaling is important in modulating cellular function, and a dysfunctional neuronal NO synthase (nNOS) may contribute to an ineffective muscle function. This study investigated nNOS expression and localization in chronically painful muscle. Forty-one women clinically diagnosed with trapezius myalgia (MYA) and 18 healthy controls (CON) were included in the case-control study. Subsequently, MYA were randomly assigned to either 10 weeks of specific strength training (SST, n = 18), general fitness training (GFT, n = 15), or health information (REF, n = 8). Distribution of fiber type, cross-sectional area, and sarcolemmal nNOS expression did not differ between MYA and CON. However, MYA showed increased sarcoplasmic nNOS localization (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) compared with CON. SST resulted in a decrease of sarcoplasm-localized nNOS following training (before 18.1 ± 12 versus after 12.0 ± 12%; P = 0,027). We demonstrate that myalgic muscle displays altered nNOS localization and that 10 weeks of strength training normalize these disruptions, which supports previous findings of impaired muscle oxygenation during work tasks and reduced pain following exercise.

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Related in: MedlinePlus

Trapezius myalgia shows sarcoplasm-localized nNOS. Data from the case-control study showed an increased proportion of muscle fibers with nNOS protein localized in the sarcoplasm in trapezius myalgia (MYA) patients compared to healthy controls (CON) detected by immunohistochemistry. 18.8 ± 12 versus 12.8 ± 8%, P = 0.049.
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fig2: Trapezius myalgia shows sarcoplasm-localized nNOS. Data from the case-control study showed an increased proportion of muscle fibers with nNOS protein localized in the sarcoplasm in trapezius myalgia (MYA) patients compared to healthy controls (CON) detected by immunohistochemistry. 18.8 ± 12 versus 12.8 ± 8%, P = 0.049.

Mentions: The number of fibers counted per subject was 292+/− 43 (MYA) and 302+/− 82 (CON). No difference was observed in distribution of type I/II fibers and mean CSA between MYA patients and CON (Table 1). NADPH diaphorase activity staining of trapezius muscle revealed lower nNOS activity in the sarcolemma and higher activity in the sarcoplasm of type I fibers compared to type II fibers (Figure 1(a)). Based on evaluations of immunohistochemical staining of nNOS from all subjects, approximately 50% of the muscle fibers in both MYA and CON showed either loss of (nNOS−) or reduced amounts of (nNOS+) sarcolemmal-localized nNOS (Table 1; Figure 1(b)). The remaining 50% of muscle fibers expressed normal levels of nNOS (nNOS++). Notably, an increased proportion of fibers in MYA presented with nNOS protein localized to the sarcoplasm compared to CON (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) (Table 1 and Figure 2). For purposes of comparison with trapezius muscle an image of nNOS expression in healthy vastus lateralis muscle is included (Figure 1(b)).


Neuronal nitric oxide synthase is dislocated in type I fibers of myalgic muscle but can recover with physical exercise training.

Jensen L, Andersen LL, Schrøder HD, Frandsen U, Sjøgaard G - Biomed Res Int (2015)

Trapezius myalgia shows sarcoplasm-localized nNOS. Data from the case-control study showed an increased proportion of muscle fibers with nNOS protein localized in the sarcoplasm in trapezius myalgia (MYA) patients compared to healthy controls (CON) detected by immunohistochemistry. 18.8 ± 12 versus 12.8 ± 8%, P = 0.049.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4380094&req=5

fig2: Trapezius myalgia shows sarcoplasm-localized nNOS. Data from the case-control study showed an increased proportion of muscle fibers with nNOS protein localized in the sarcoplasm in trapezius myalgia (MYA) patients compared to healthy controls (CON) detected by immunohistochemistry. 18.8 ± 12 versus 12.8 ± 8%, P = 0.049.
Mentions: The number of fibers counted per subject was 292+/− 43 (MYA) and 302+/− 82 (CON). No difference was observed in distribution of type I/II fibers and mean CSA between MYA patients and CON (Table 1). NADPH diaphorase activity staining of trapezius muscle revealed lower nNOS activity in the sarcolemma and higher activity in the sarcoplasm of type I fibers compared to type II fibers (Figure 1(a)). Based on evaluations of immunohistochemical staining of nNOS from all subjects, approximately 50% of the muscle fibers in both MYA and CON showed either loss of (nNOS−) or reduced amounts of (nNOS+) sarcolemmal-localized nNOS (Table 1; Figure 1(b)). The remaining 50% of muscle fibers expressed normal levels of nNOS (nNOS++). Notably, an increased proportion of fibers in MYA presented with nNOS protein localized to the sarcoplasm compared to CON (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) (Table 1 and Figure 2). For purposes of comparison with trapezius muscle an image of nNOS expression in healthy vastus lateralis muscle is included (Figure 1(b)).

Bottom Line: Distribution of fiber type, cross-sectional area, and sarcolemmal nNOS expression did not differ between MYA and CON.However, MYA showed increased sarcoplasmic nNOS localization (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) compared with CON.SST resulted in a decrease of sarcoplasm-localized nNOS following training (before 18.1 ± 12 versus after 12.0 ± 12%; P = 0,027).

View Article: PubMed Central - PubMed

Affiliation: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, 5000 Odense C, Denmark ; Institute of Clinical Research, Pathology and SDU Muscle Research Cluster, University of Southern Denmark, 5230 Odense M, Denmark.

ABSTRACT
Trapezius myalgia is the most common type of chronic neck pain. While physical exercise reduces pain and improves muscle function, the underlying mechanisms remain unclear. Nitric oxide (NO) signaling is important in modulating cellular function, and a dysfunctional neuronal NO synthase (nNOS) may contribute to an ineffective muscle function. This study investigated nNOS expression and localization in chronically painful muscle. Forty-one women clinically diagnosed with trapezius myalgia (MYA) and 18 healthy controls (CON) were included in the case-control study. Subsequently, MYA were randomly assigned to either 10 weeks of specific strength training (SST, n = 18), general fitness training (GFT, n = 15), or health information (REF, n = 8). Distribution of fiber type, cross-sectional area, and sarcolemmal nNOS expression did not differ between MYA and CON. However, MYA showed increased sarcoplasmic nNOS localization (18.8 ± 12 versus 12.8 ± 8%, P = 0.049) compared with CON. SST resulted in a decrease of sarcoplasm-localized nNOS following training (before 18.1 ± 12 versus after 12.0 ± 12%; P = 0,027). We demonstrate that myalgic muscle displays altered nNOS localization and that 10 weeks of strength training normalize these disruptions, which supports previous findings of impaired muscle oxygenation during work tasks and reduced pain following exercise.

Show MeSH
Related in: MedlinePlus