Effects of Intermittent Weight-Bearing and Clenbuterol on Disuse Atrophy of Rat Hindlimb Muscles

Yamazaki, Toshiaki

doi:10.1298/jjpta.8.9

Cited by 6 publications

(13 citation statements)

References 52 publications

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“…The results suggest that Cb exerts anabolic effects that are load-dependent and musclespecific. Our previous study 13) also demonstrated that Cb alone could suppress a decline in muscle weight with no effect on contractility, while IWB alone suppressed a decline in muscle contractile properties but had little effect on muscle morphological characteristics. The combination of IWB and Cb was useful in suppressing atrophy in type I fiber-predominant SOL 13) .…”

mentioning

confidence: 81%

“…Then the muscle was mounted onto a force-recording device (LTS-500GA, Kyowa, Japan) and bathed in Ringer's solution (25 C) which had been aerated with gas (95%O 2 / 5%CO 2 ). The muscle was stretched to 110% of its resting length and stimulated with a supramaximal square wave (0.2 ms duration) delivered via two parallel platinum electrodes using an electric stimulator (SC6, Medelec, UK) 13) . Contractile responses were recorded and analyzed on an analog-to-digital converter coupled to a computer.…”

Section: Muscle Preparation / Measurement Of Contractile Propertiesmentioning

confidence: 99%

“…The stained sections were examined with an image analysis system consisting of a light photomicroscope (BX-50; Olympus), personal computer (Power Macintosh G3) and image processing software (NIH Image 1.62) 13) . The muscle fiber type proportion and the CSA of more than 200 total muscle fibers in four fields from each muscle were measured.…”

Section: Histochemical Analysismentioning

confidence: 99%

“…Muscle protein concentration was obtained using a modification 13) of the technique described by Wineski et al 12) and Caiozzo et al 23) . All tissue preparations were performed on ice with buffer at 4 C.…”

Section: Biochemical Analysismentioning

confidence: 99%

“…A hypothesis underlying this study was that stretching would affect the contractile properties and Cb would affect morphological characteristics thus justifying the clinical use of stretching in combination with Cb. Additionally, the effects of combined stretching and Cb medication was compared to the effects of combined IWB and Cb medication in previous study 13) .…”

mentioning

confidence: 99%

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

Yamazaki

Yokogawa

Tachino

2009

J Jpn Phys Ther Assoc

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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 ...

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mentioning

confidence: 81%

Section: Muscle Preparation / Measurement Of Contractile Propertiesmentioning

confidence: 99%

Section: Histochemical Analysismentioning

confidence: 99%

Section: Biochemical Analysismentioning

confidence: 99%

mentioning

confidence: 99%

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

Yamazaki

Yokogawa

Tachino

2009

J Jpn Phys Ther Assoc

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An accumulation of muscle macrophages is accompanied by altered insulin sensitivity after reduced activity and recovery

et al. 2019

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Background Mechanisms underlying physical inactivity‐induced insulin resistance are not well understood. In addition to a role in muscle repair, immune cell populations such as macrophages may regulate insulin sensitivity. Aim The aim of this study was to examine if the dynamic changes in insulin sensitivity during and after recovery from reduced physical activity corresponded to changes in skeletal muscle macrophages. Methods In this prospective clinical study, we collected muscle biopsies from healthy older adults (70 ± 2 years, n = 12) before and during a hyperinsulinaemic‐euglycaemic clamp and this occurred before (PRE) and after 2‐week reduced physical activity (RA), and following 2‐week of recovery (REC). Insulin sensitivity (hyperinsulinaemic‐euglycaemic clamp), skeletal muscle mRNA expression of inflammatory markers, and immunofluorescent quantification of skeletal muscle macrophages, myofibre‐specific satellite cell and capillary content were assessed. Results Insulin sensitivity was decreased following reduced activity and rebounded following recovery above PRE levels. We observed an increase (P < 0.01) in muscle macrophages (CD68+CD206+: 190 [55, 324]; CD11b+CD206+: 117 [28, 205]% change from PRE) and CD68 (2.4 [1.4, 3.4]‐fold) and CCL2 (1.9 [1.3, 2.5]‐fold) mRNA following RA concurrent with increased (P < 0.03) satellite cells (55 [6, 104]%) in slow‐twitch myofibres. Moreover, the distance of satellite cells to the nearest capillary was increased 7.7 (1.7, 13.7) µm in fast‐twitch myofibres at RA (P = 0.007). Changes in macrophages were positively associated with increased insulin sensitivity following RA (R > 0.57, P < 0.05). Conclusion These findings suggested that a dynamic response of skeletal muscle macrophages following acute changes in physical activity in healthy older adults is related to insulin sensitivity.

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Sarcopenia: Aging-Related Loss of Muscle Mass and Function

Larsson

Degens

et al. 2019

Physiological Reviews

959

728

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Sarcopenia is a loss of muscle mass and function in the elderly that reduces mobility, diminishes quality of life, and can lead to fall-related injuries, which require costly hospitalization and extended rehabilitation. This review focuses on the aging-related structural changes and mechanisms at cellular and subcellular levels underlying changes in the individual motor unit: specifically, the perikaryon of the α-motoneuron, its neuromuscular junction(s), and the muscle fibers that it innervates. Loss of muscle mass with aging, which is largely due to the progressive loss of motoneurons, is associated with reduced muscle fiber number and size. Muscle function progressively declines because motoneuron loss is not adequately compensated by reinnervation of muscle fibers by the remaining motoneurons. At the intracellular level, key factors are qualitative changes in posttranslational modifications of muscle proteins and the loss of coordinated control between contractile, mitochondrial, and sarcoplasmic reticulum protein expression. Quantitative and qualitative changes in skeletal muscle during the process of aging also have been implicated in the pathogenesis of acquired and hereditary neuromuscular disorders. In experimental models, specific intervention strategies have shown encouraging results on limiting deterioration of motor unit structure and function under conditions of impaired innervation. Translated to the clinic, if these or similar interventions, by saving muscle and improving mobility, could help alleviate sarcopenia in the elderly, there would be both great humanitarian benefits and large cost savings for health care systems.

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Effects of Intermittent Weight-Bearing and Clenbuterol on Disuse Atrophy of Rat Hindlimb Muscles

Cited by 6 publications

References 52 publications

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

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

An accumulation of muscle macrophages is accompanied by altered insulin sensitivity after reduced activity and recovery

Sarcopenia: Aging-Related Loss of Muscle Mass and Function

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