Skeletal Muscle Protein Synthesis and Growth Hormone Secretion in Young Lambs Treated with Clenbuterol

Claeys, M. C.; Mulvaney, D. R.; McCarthy, F. D.; Gore, M.; Marple, D. N.; Sartin, James L.

doi:10.2527/jas1989.6792245x

Cited by 73 publications

(24 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ratio of heart weight to tibial length significantly increased in Clen-treated animals. However, the ratio of heart weight to body weight did not change after Clen administration, presumably because of the increase in body weight due to skeletal muscle hypertrophy (3,7,16). It could be argued that after the increase in body mass, a proportional increase in cardiac output and blood flow is expected; the myocyte hypertrophy observed could therefore be the consequence of pressure-volume overload rather than a direct effect of Clen.…”

Section: Discussionmentioning

confidence: 94%

Effects of chronic administration of clenbuterol on function and metabolism of adult rat cardiac muscle

Soppa¹,

Smolenski²,

Latif³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

. Effects of chronic administration of clenbuterol on function and metabolism of adult rat cardiac muscle. Am J Physiol Heart Circ Physiol 288: H1468 -H1476, 2005. First published November 4, 2004 doi: 10.1152/ajpheart.00624.2004, a ␤2-agonist, is known to produce skeletal and myocardial hypertrophy. This compound has recently been used in combination with left ventricular assist devices for the treatment of end-stage heart failure to reverse or prevent the adverse effects of unloading-induced myocardial atrophy. However, the mechanisms of action of Clen on myocardial cells have not been fully elucidated. In an attempt to clarify this issue, we examined the effects of chronic administration of Clen on Ca 2ϩ handling and substrate preference in cardiac muscle. Rats were treated with either 2 mg ⅐ kg Ϫ1 ⅐ day Ϫ1 Clen or saline (Sal) for 4 wk with the use of osmotic minipumps. Ventricular myocytes were enzymatically dissociated. Cells were field stimulated at 0.5, 1, and 2 Hz, and cytoplasmic Ca 2ϩ transients were monitored with the use of the fluorescent indicator indo-1 acetoxymethyl ester. Two-dimensional surface area and action potentials in current clamp were also measured. We found that in the Clen group there was significant hypertrophy at the organ and cellular levels compared with Sal. In Clen myocytes, the amplitude of the indo-1 ratio transients was significantly increased. Sarcoplasmic reticulum Ca 2ϩ content, estimated by rapid application of 20 mM caffeine, was significantly increased in the Clen group. The action potential was prolonged in the Clen group compared with Sal. Carbohydrate contribution to the tricarboxylic cycle (Krebs cycle) flux was increased several times in the Clen group. This increase was associated with decreased expression of peroxisome proliferator-activated receptor-␣. This study shows that chronic administration of Clen induces cellular hypertrophy and increases oxidative carbohydrate utilization together with an increase in sarcoplasmic reticulum Ca 2ϩ content, which results in increased amplitude of the Ca 2ϩ transients. These effects could be important when Clen is used in conjunction with left ventricular assist devices treatment.sarcoplasmic reticulum Ca 2ϩ content; tricarboxylic cycle; left ventricular assist devices LONG-TERM LEFT VENTRICULAR (LV) assist device (LVAD) support has been shown to improve survival and quality of life in patients with advanced heart failure and contraindications to cardiac transplantation (22). LVAD support is also routinely used as a bridge to transplantation in patients with end-stage heart failure. In a number of patients, with the use of this strategy in association with pharmacological therapy (combination therapy), a significant improvement in myocardial performance has been observed. In some cases the mechanical device could be explanted without resorting to heart transplantation ("bridge to recovery") (11-13, 27, 40).LVAD support results in profound and complex changes in the structure and function of the myocardium, which include "...

show abstract

Section: Discussionmentioning

confidence: 94%

Effects of chronic administration of clenbuterol on function and metabolism of adult rat cardiac muscle

Soppa¹,

Smolenski²,

Latif³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

View full text Add to dashboard Cite

show abstract

“…Increased muscle mass and contractility after administration of 2 agonists have been explained by increased protein synthesis, decreased protein degradation, changes in water content, changes in phosphorylation of intracellular proteins and, possible androgenic activity (Reeds et al 1986;Maltin et al 1987;Zeman et al 1987;Claeys et al 1989;Bates and Pell 1991;Benson et al1991;Cartaña and Stock 1994;Cartaña and Stock 1995;Dodd et al 1996;Von Bueren et al 2007). An involvement of L-type calcium channels has been found to be an unlikely contributor (Murphy et al 1999a).…”

Section: Discussionmentioning

confidence: 96%

Effects of β2-adrenergic stimulation on exercise capacity in normal subjects

et al. 2011

View full text Add to dashboard Cite

β2-Adrenergic receptor agonists are believed to present with ergogenic properties. However, how combined respiratory, cardiovascular and muscular effects of these drugs might affect exercise capacity remain incompletely understood. The effects of salbutamol were investigated in 23 healthy subjects. The study was randomised, placebo-controlled in double-blind and followed a cross-over design. Salbutamol was given at the dose of 10 μg/min in 11 subjects and 20 μg/min iv in the other 12 subjects. Measurements included muscle sympathetic nerve activity (MSNA), ventilatory responses to hyperoxic hypercapnia (7% CO(2) in O(2,) central chemoreflex), isocapnic hypoxia (10% O(2) in N(2), peripheral chemoreflex) and isometric muscle contraction followed by a local circulatory arrest (metaboreflex), cardiopulmonary exercise test (CPET) variables and isokinetic muscle strength. Salbutamol 10 μg/min increased heart rate and blood pressure, while MSNA burst frequency remained unchanged. Peripheral chemosensitivity increased, as evidenced by an increased ventilatory response to hypoxia, but ventilatory responses to hypercapnia or muscle ischaemia remained unchanged. The effects of salbutamol 20 μg/min were similar. Both doses of salbutamol did not affect CPET. Only the higher dose of salbutamol decreased the anaerobic threshold, but this was not associated with a change in VO(2) max. Salbutamol increased the slopes of ventilation as a function of VO(2) (P < 0.05) and VCO(2) (P < 0.001) during CPET. Maximal isokinetic muscle strength was not affected by salbutamol. In conclusion, the acute administration of either low or high dose salbutamol does not affect exercise capacity in normal subjects, in spite of an earlier anaerobic threshold and increased chemosensitivity.

show abstract

“…The basis for the effectiveness of clenbuterol as an anabolic agent has been attributed to its ability to promote muscle protein synthesis (90,93,129,201,281,372,377) as well as reduce muscle protein degradation (39,51,139,278,281,372,454). There has been much debate as to whether the clenbuterol-induced increase in muscle mass is due preferentially to one mechanism or the other (34).…”

Section: Growth-promoting Effects Of ␤-Agonistsmentioning

confidence: 97%

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

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.

show abstract

Skeletal Muscle Protein Synthesis and Growth Hormone Secretion in Young Lambs Treated with Clenbuterol

Cited by 73 publications

References 0 publications

Effects of chronic administration of clenbuterol on function and metabolism of adult rat cardiac muscle

Effects of chronic administration of clenbuterol on function and metabolism of adult rat cardiac muscle

Effects of β2-adrenergic stimulation on exercise capacity in normal subjects

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

Contact Info

Product

Resources

About