Effects of β<sub>2</sub>-agonist clenbuterol on biochemical and  contractile properties of unloaded soleus fibers of rat

Ricart-Firinga, Carole; Stevens, Laurence; Canu, Marie‐Hélène; Nemirovskaya, T. L.; Mounier, Yvonne

doi:10.1152/ajpcell.2000.278.3.c582

Cited by 50 publications

(63 citation statements)

References 32 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After 2 weeks of salbutamol administration, we observed a more pronounced effect on fiber composition than on the anabolic response, in agreement with data reported by Ricart-Firinga et al (7). Over 14 days the number of type II fibers increased significantly from the initial 10% observed in healthy soleus up to 21%, in agreement with data reported by Zeman et al (8).…”

Section: Discussionsupporting

confidence: 93%

“…Furthermore, the hypertrophic effect of BAA seems to be selective for certain fiber types. Most studies have demonstrated that BAA increase the cross-sectional area of fast muscle fibers (7)(8)(9) while the results of studies of the effects of BAA on slow muscle fibers have not been consistent. Some studies have demonstrated that the cross-sectional area of slow twitch oxidative fibers is not changed by chronic administration of BAA (8,10,11) while others have shown that all fiber types are affected equally (12,13).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effect of salbutamol on innervated and denervated rat soleus muscle

Šoić-Vranić

Bobinac

Bajek

et al. 2005

Braz J Med Biol Res

View full text Add to dashboard Cite

The objective of the present investigation was to perform a 14-day time-course study of treatment with salbutamol, a ß 2 adrenoceptor agonist, on rat soleus muscle in order to assess fiber type selectivity in the hypertrophic response and fiber type composition. Male Wistar rats were divided into four groups: control (N = 10), treated with salbutamol (N = 30), denervated (N = 30), and treated with salbutamol after denervation (N = 30). Salbutamol was injected intraperitoneally in the rats of the 2nd and 4th groups at a concentration of 0.3 mg/kg twice a day for 2 weeks. The muscles were denervated using the crush method with pean. The animals were sacrificed 3, 6, 9, 12, and 14 days after treatment. Frozen cross-sections of soleus muscle were stained for myosin ATPase, pH 9.4. Cross-sectional area and percent of muscle fibers were analyzed morphometrically by computerized image analysis. Treatment with salbutamol induced hypertrophy of all fiber types and a higher percentage of type II fibers (21%) in the healthy rat soleus muscle. Denervation caused marked atrophy of all fibers and conversion from type I to type II muscle fibers. Denervated muscles treated with salbutamol showed a significantly larger crosssectional area of type I muscle fibers, 28.2% compared to the denervated untreated muscle. Moreover, the number of type I fibers was increased. These results indicate that administration of salbutamol is able to induce changes in cross-sectional area and fiber type distribution in the early phase of treatment. Since denervation-induced atrophy and conversion from type I to type II fibers were improved by salbutamol treatment we propose that salbutamol, like other ß 2 adrenoceptor agonists, may have a therapeutic potential in improving the condition of skeletal muscle after denervation.

show abstract

Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Effect of salbutamol on innervated and denervated rat soleus muscle

Šoić-Vranić

Bobinac

Bajek

et al. 2005

Braz J Med Biol Res

View full text Add to dashboard Cite

show abstract

“…As a reason for these results, the possibility of the difference (time lag) in calcium dynamics by the sarcoplasmic reticulum (SR) during fiber type shifts was suspected. Many studies have reported Cb-induced shifts from slowtwitch (type I) toward fast-twitch (type II) fiber types in SOL [26][27][28][29] . Contraction time and one-half relaxation time are indicative of calcium release and uptake by SR respectively 21) .…”

Section: Discussionmentioning

confidence: 99%

“…If a benefit is expected for the patient who cannot bear weight, and if the patient consents to it in advance, the use of combined stretching and Cb medication may provide a valid means of minimizing disuse muscle atrophy and the loss of muscle strength 8,31) . However, considering that Cb medication alone can have an adverse effect [26][27][28][29] of converting slow fibers into fast fibers, it is essential that Cb not be used alone but be combined with physical therapy in the form of stretching. Complete prevention of atrophy using the intervention (stretching alone) approximately one hour daily may be difficult.…”

Section: Discussionmentioning

confidence: 99%

Effects of Combined Stretching and Clenbuterol on Disuse Atrophy in Rat Soleus Muscle

Yamazaki

Yokogawa

Tachino

2009

J Jpn Phys Ther Assoc

View full text Add to dashboard Cite

ABSTRACT. Background and Purpose: Clinically, disuse muscle atrophy is often seen among patients who are severely debilited and are on prolonged bed rest. Common physical therapy interventions are not successful in preventing disuse muscle atrophy early in the medical treatment of critically ill patients. In situations such as this, the use of a 2-adrenergic agonist such as clenbuterol (Cb) may be of benefit in preventing atrophy. Also, recent studies have suggested that stretching is possible in preventing disuse muscle atrophy and the decline in muscle strength. The objective of this study was to evaluate the effects of Cb medication combined with stretching (ST) on rat soleus muscle (SOL) during the progression of disuse muscle atrophy. Subjects: Thirty-five male Wistar rats were used in this study. Methods: The rats were divided into five groups: control (CON), hindlimb-unweighting (HU) only, HU+ST, HU+Cb medication, and HU+ST+Cb groups. The right SOL in stretching groups was maintained a stretched position for one hour daily by passively dorsiflexing the ankle joint under non-anesthesia. The experimental period was 2 weeks. Results: In the ST group, peak twitch tension per cross-sectional area in soleus muscle was significantly larger than in the Cb group, while there was no significant difference between the CON and ST groups. The conversion of type I to type II fibers that was observed in the Cb group was not recognized in the combined ST and Cb group. Discussion and Conclusion: Distinct effect of combined stretching and Cb medication was not recognized statistically. The results indicate that Cb affects muscle morphological characteristics while stretching affects contractile properties. These data suggest that a combined ST and Cb intervention considered the type-specificity of muscle fiber may be need more consideration for preventing disuse muscle atrophy and the decline in muscle strength. Key words: stretching, clenbuterol, disuse muscle atrophy, rat, atrophy prevention (J Jpn Phys Ther Assoc 12: 13-19, 2009) Disuse muscle atrophy has a substantial effect on activities of daily living (ADL) such as standing and walking 1,2) . Clinically, disuse muscle atrophy is often seen among patients who are severely debilitated and have been on prolonged bed rest in an acute care setting. Early initiation of weight-bearing activities such as ambulation in the clinical course of a patient's critical illness has been advocated to prevent disuse atrophy of lower extremity muscles. However, due to underlying illness, early weightbearing exercises are often contraindicated. While hindlimb unweighting (HU) has been used as a model for spaceflight, it is also used as a model for decreased muscle use. On the basis of the results from a study in rats, Brown et al. 3) reported that one hour of weightbearing per day, during two weeks of HU, is useful in suppressing the progression of disuse atrophy in soleus muscle (SOL). We have also been exploring effective means of preventing atrophy by using a clinically applicable ...

show abstract

“…We found that in rat masseter muscle, the bite-opening treatment (i.e., a mechanical overload) produced not only the up-regulation of MHC IIa mRNA at the expense of MHC IIb mRNA independently of CaN-signaling pathways, but also the MHC mRNA transition from IIa to I and the muscle mass maintenance of type IIb fiber through CaN-signaling pathways [9]. However, the role of CaN in muscle growth and fiber-type transformations has long been a matter of debate [25,[27][28][29][30].Clenbuterol (CB), a β 2 -adrenergic agonist, is also known to induce not only muscle hypertrophy, as induced by the bite-opening treatment, but also slow-to-fast fibertype transition (i.e., transition opposite to the fibertype transitions induced by the bite-opening treatment) [16,17,[31][32][33][34]. This implies that the CB treatment and the biteopening treatment might activate the same intracellular signalingpathways for changing the muscle mass, but different intracellular signaling-pathways for the fibertype changes.…”

mentioning

confidence: 99%

Effects of Clenbuterol and Cyclosporin A on the Myosin Heavy Chain mRNA Level and the Muscle Mass in Rat Masseter

et al. 2006

View full text Add to dashboard Cite

Abstract:To gain more insight into the molecular mechanism of muscle growth and fiber-type transformations, we analyzed the effects of β 2 -adrenergic agonist clenbuterol (CB) and/or cyclosporin A (CsA), a potent inhibitor of calcineurin (CaN), on the muscle mass as well as on the mRNA levels of myosin heavy chains (MHC I, IIa, IId/x, IIb), using a real-time RT-PCR with specific primers in rat masseter. In comparison with control, the CB treatment significantly decreased the MHC I mRNA level (p < 0.01), but increased the MHC IId/x mRNA level (p < 0.01), and the CsA treatment significantly decreased the MHC I mRNA level (p < 0.05) in association with the significant decrease in MHC IIb mRNA level (p < 0.05). The CB+CsA treatment significantly decreased the levels of MHC I (p < 0.01) and IIa mRNAs (p < 0.05), but increased the MHC IId/x mRNA level (p < 0.001) in association with a significant decrease in MHC IIb mRNA level (p < 0.01), in comparison with control. The masseter muscle mass was significantly (p < 0.001) increased by either the CB or the CB + CsA treatment, but decreased with the CsA treatment (p < 0.01). These results suggest that in rat masseter muscle, CB has an anabolic action accompanying MHC mRNA I → IIa → IId/x sequence transition independently of CaN-signaling pathways, and CaN is involved in the type I fiber gene expression and the muscle mass maintenance of type IIb fiber.Key words: myosin heavy chain mRNA, muscle mass, clenbuterol, cyclosporin A, real time RT-PCR.Masticatory muscles have been known to be capable of adapting their mass and muscle phenotypes to meet a wide range of functional demands [1][2][3][4][5][6][7][8][9], as in limb muscles [10][11][12][13][14][15][16]. However, most of the studies on masticatory muscles to date have focused on describing the results rather than analyzing the molecular mechanism of muscle mass alteration and fibertype conversion. We have been particularly interested in the way mechanical signals influence the expression of subsets of genes, which determine muscle mass and phenotype. Pharmacological approaches have been used to dissect the signaling pathways that mediate the effect of mechanical load on muscle mass and phenotypes [9,[16][17][18]. A signaling mechanism involving calcineurin (CaN) has recently been suggested to promote the muscle growth as well as fibertype transformations [19][20][21][22][23][24][25][26]. The in vivo administration of cyclosporin A (CsA), a potent inhibitor of CaN, has been shown to prevent the fast-to-slow myosin heavy chain (MHC) isoform transition induced by the functional overload [18]. We found that in rat masseter muscle, the bite-opening treatment (i.e., a mechanical overload) produced not only the up-regulation of MHC IIa mRNA at the expense of MHC IIb mRNA independently of CaN-signaling pathways, but also the MHC mRNA transition from IIa to I and the muscle mass maintenance of type IIb fiber through CaN-signaling pathways [9]. However, the role of CaN in muscle growth and fiber-type transformations has long been ...

show abstract

Effects of β₂-agonist clenbuterol on biochemical and contractile properties of unloaded soleus fibers of rat

Cited by 50 publications

References 32 publications

Effect of salbutamol on innervated and denervated rat soleus muscle

Effect of salbutamol on innervated and denervated rat soleus muscle

Effects of Combined Stretching and Clenbuterol on Disuse Atrophy in Rat Soleus Muscle

Effects of Clenbuterol and Cyclosporin A on the Myosin Heavy Chain mRNA Level and the Muscle Mass in Rat Masseter

Contact Info

Product

Resources

About

Effects of β2-agonist clenbuterol on biochemical and contractile properties of unloaded soleus fibers of rat

Cited by 50 publications

References 32 publications

Effect of salbutamol on innervated and denervated rat soleus muscle

Effect of salbutamol on innervated and denervated rat soleus muscle

Effects of Combined Stretching and Clenbuterol on Disuse Atrophy in Rat Soleus Muscle

Effects of Clenbuterol and Cyclosporin A on the Myosin Heavy Chain mRNA Level and the Muscle Mass in Rat Masseter

Contact Info

Product

Resources

About

Effects of β₂-agonist clenbuterol on biochemical and contractile properties of unloaded soleus fibers of rat