Cardiac Muscle Contractility Following Chronic Clenbuterol Administration and Exercise 1038

Duncan, N. D.; Lynch, Gordon S.; Jones, D. D.; Williams, David A.

doi:10.1097/00005768-199605001-01035

Cited by 2 publications

(3 citation statements)

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“…On the contrary, rats administered high doses of clenbuterol (2 mg/kg) daily for several months showed significant cardiac hypertrophy, infiltration of collagen in the left ventricular walls (123), and impaired cardiac mechanics, including reductions in left ventricular pressure (122). Histological examination of the myocardium of dogs following chronic treatment with isoprenaline (in mg/kg doses) revealed severe necrosis (220), while congestion, interstitial edema, hypertrophy of muscle fibers, and myocardial necrosis were evident in rats given very large doses (between 17 and 150 mg/kg daily) of another ␤-agonist, salbutamol, for 1 mo (256).…”

Section: A Effects Of ␤-Agonists On Cardiac Muscle Structure and Funmentioning

confidence: 99%

“…However, some authors have made interspecies comparisons based on metabolic measurements. For example, Maltin et al (279) suggested that a dose of 10 g/kg for the rat was equivalent to 1.0 g/kg for humans, a dose considered to be safe (121,122). Even if a theoretical safe dosage of clenbuterol was prescribed for promoting muscle mass in humans, it is unlikely that this level would be adhered to by bodybuilders given that some of these athletes are notorious for taking anabolic steroids in excess of 26 times the therapeutic dose (59,88,122).…”

Section: B Use Of ␤-Agonists By Athletes For Performance Enhancementmentioning

confidence: 99%

“…For example, Maltin et al (279) suggested that a dose of 10 g/kg for the rat was equivalent to 1.0 g/kg for humans, a dose considered to be safe (121,122). Even if a theoretical safe dosage of clenbuterol was prescribed for promoting muscle mass in humans, it is unlikely that this level would be adhered to by bodybuilders given that some of these athletes are notorious for taking anabolic steroids in excess of 26 times the therapeutic dose (59,88,122). Another confounding issue is the fact that many bodybuilders take more than one drug at any one time, and the supposed increases in muscle mass following clenbuterol administration are hard to gauge when, for example, it is taken in conjunction with either one or more anabolic steroids.…”

Section: B Use Of ␤-Agonists By Athletes For Performance Enhancementmentioning

confidence: 99%

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Role of β-Adrenoceptor Signaling in Skeletal Muscle: Implications for Muscle Wasting and Disease

Lynch¹,

Ryall²

2008

Physiological Reviews

363

356

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The importance of beta-adrenergic signaling in the heart has been well documented, but it is only more recently that we have begun to understand the importance of this signaling pathway in skeletal muscle. There is considerable evidence regarding the stimulation of the beta-adrenergic system with beta-adrenoceptor agonists (beta-agonists). Although traditionally used for treating bronchospasm, it became apparent that some beta-agonists could increase skeletal muscle mass and decrease body fat. These so-called "repartitioning effects" proved desirable for the livestock industry trying to improve feed efficiency and meat quality. Studying beta-agonist effects on skeletal muscle has identified potential therapeutic applications for muscle wasting conditions such as sarcopenia, cancer cachexia, denervation, and neuromuscular diseases, aiming to attenuate (or potentially reverse) the muscle wasting and associated muscle weakness, and to enhance muscle growth and repair after injury. Some undesirable cardiovascular side effects of beta-agonists have so far limited their therapeutic potential. This review describes the physiological significance of beta-adrenergic signaling in skeletal muscle and examines the effects of beta-agonists on skeletal muscle structure and function. In addition, we examine the proposed beneficial effects of beta-agonist administration on skeletal muscle along with some of the less desirable cardiovascular effects. Understanding beta-adrenergic signaling in skeletal muscle is important for identifying new therapeutic targets and identifying novel approaches to attenuate the muscle wasting concomitant with many diseases.

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Section: A Effects Of ␤-Agonists On Cardiac Muscle Structure and Funmentioning

confidence: 99%

Section: B Use Of ␤-Agonists By Athletes For Performance Enhancementmentioning

confidence: 99%

Section: B Use Of ␤-Agonists By Athletes For Performance Enhancementmentioning

confidence: 99%

See 1 more Smart Citation

Role of β-Adrenoceptor Signaling in Skeletal Muscle: Implications for Muscle Wasting and Disease

Lynch¹,

Ryall²

2008

Physiological Reviews

363

356

View full text Add to dashboard Cite

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Skeletal muscle myosin heavy chain isoforms and energy metabolism after clenbuterol treatment in the rat

Rajab

Fox

Riaz

et al. 2000

American Journal of Physiology-Regulatory, Integrative and Comp

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Prolonged treatment with the beta(2)-adrenoceptor agonist clenbuterol (1-2 mg. kg body mass(-1). day (-1)) is known to induce the hypertrophy of fast-contracting fibers and the conversion of slow- to fast-contracting fibers. We investigated the effects of administering a lower dose of clenbuterol (250 microgram. kg body mass(-1). day (-1)) on skeletal muscle myosin heavy chain (MyHC) protein isoform content and adenine nucleotide (ATP, ADP, and AMP) concentrations. Male Wistar rats were administered clenbuterol (n = 8) or saline (n = 6) subcutaneously for 8 wk, after which the extensor digitorum longus (EDL) and soleus muscles were removed. We demonstrated an increase of type IIa MyHC protein content in the soleus from approximately 0.5% in controls to approximately 18% after clenbuterol treatment (P < 0.05), which was accompanied by an increase in the total adenine nucleotide pool (TAN; approximately 19%, P < 0.05) and energy charge [E-C = (ATP + 0.5 ADP)/(ATP + ADP + AMP); approximately 4%; P < 0.05]. In the EDL, a reduction in the content of the less prevalent type I MyHC protein from approximately 3% in controls to 0% after clenbuterol treatment (P < 0.05) occurred without any alterations in TAN and E-C. These findings demonstrate that the phenotypic changes previously observed in slow muscle after clenbuterol administration at 1-2 mg. kg body mass(-1). day(-1) are also observed at a substantially lower dose and are paralleled by concomitant changes in cellular energy metabolism.

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Cardiac Muscle Contractility Following Chronic Clenbuterol Administration and Exercise 1038

Cited by 2 publications

References 0 publications

Role of β-Adrenoceptor Signaling in Skeletal Muscle: Implications for Muscle Wasting and Disease

Role of β-Adrenoceptor Signaling in Skeletal Muscle: Implications for Muscle Wasting and Disease

Skeletal muscle myosin heavy chain isoforms and energy metabolism after clenbuterol treatment in the rat

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