Effect of Contractile Activity on Rat Skeletal Muscle  -Adrenoceptor Properties

Fell, R. D.; Lizzo, Florence H.; Cervoni, Peter; Crandall, David L.

doi:10.3181/00379727-180-42212

Cited by 15 publications

(17 citation statements)

References 5 publications

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“…Comparing these values reported in rats with those of trout RM and WM (Table 1) indicates slightly higher affinities in trout but approximately two-to five-fold lower B max values. The trend of higher binding site numbers in RM compared with WM was retained, as reported in other mammalian studies that used other radiolabeled ligands and/or preparations (13,21,33,45). Possible contamination by vascular tissue is considered to be an insignificant contributing factor to the higher binding site numbers in RM compared with WM because Ͻ3% of the RM volume is vascular tissue (6).…”

Section: Discussionsupporting

confidence: 61%

The rainbow trout skeletal muscle β-adrenergic system: characterization and signaling

Lortie

Moon

2003

American Journal of Physiology-Regulatory, Integrative and Comp

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The presence and functionality of β-adrenoceptors (β-ARs) were examined in red (RM) and white muscle (WM) membranes isolated from the rainbow trout Oncorhynchus mykiss. Specific binding assays revealed the presence of a single class of binding sites with similar affinities in both muscle types ( K d in nM: 0.14 ± 0.03 and 0.18 ± 0.03 for RM and WM, respectively) but with a significantly higher number of binding sites in RM compared with WM (Bmax in fmol/mg protein: 3.22 ± 0.11 and 2.60 ± 0.13, respectively). Selective and nonselective β-adrenergic agonists (β-AAs) and antagonists indicated an atypical β-AR pharmacology. This result may represent a nonmammalian β-AR classification or, more likely, the presence of more than one β-AR subtype in trout muscles with similar affinities that could not be kinetically resolved. Adenylyl cyclase (ACase) assays showed a dose-dependent increase in cAMP production as concentrations of β2-AAs increased in both muscle membranes with significantly higher basal cAMP production in RM compared with WM (cAMP production in pmol cAMP · mg protein−1 · 10 min−1: 24.67 ± 3.06 and 9.64 ± 3.45, respectively). The agonist-induced increase in cAMP production was blocked by the β-adrenergic antagonist propranolol, while the ACase activator forskolin increased cAMP production by 7- to 14-fold above basal and ∼3-fold above all β-AAs tested. This study demonstrated the presence of atypical β2-ARs on RM and WM membranes of trout, suggesting that β2-AAs may be a tool to enhance protein accretion through this signaling pathway.

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Section: Discussionsupporting

confidence: 61%

The rainbow trout skeletal muscle β-adrenergic system: characterization and signaling

Lortie

Moon

2003

American Journal of Physiology-Regulatory, Integrative and Comp

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“…First, epinephrine is released into circulation during exercise (67), and intramuscular cAMP increases within minutes of treadmill running (72). Second, ␤-AR density is highest in oxidative muscles and correlates with oxidative capacity in mixed or intermediate fiber types (62,156,240); AC activity is also increased by endurance training in rats (28). Third, in cultured muscle cells, agents that induce intracellular cAMP activate oxidative enzymes, some at the level of expression (66,136).…”

Section: Camp In Functional Adaptation Of Skeletal Musclementioning

confidence: 99%

cAMP signaling in skeletal muscle adaptation: hypertrophy, metabolism, and regeneration

Berdeaux

Stewart

2012

American Journal of Physiology-Endocrinology and Metabolism

154

115

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Berdeaux R, Stewart R. cAMP signaling in skeletal muscle adaptation: hypertrophy, metabolism, and regeneration. Am J Physiol Endocrinol Metab 303: E1-E17, 2012. First published February 21, 2012 doi:10.1152/ajpendo.00555.2011.-Among organ systems, skeletal muscle is perhaps the most structurally specialized. The remarkable subcellular architecture of this tissue allows it to empower movement with instructions from motor neurons. Despite this high degree of specialization, skeletal muscle also has intrinsic signaling mechanisms that allow adaptation to long-term changes in demand and regeneration after acute damage. The second messenger adenosine 3=,5=-monophosphate (cAMP) not only elicits acute changes within myofibers during exercise but also contributes to myofiber size and metabolic phenotype in the long term. Strikingly, sustained activation of cAMP signaling leads to pronounced hypertrophic responses in skeletal myofibers through largely elusive molecular mechanisms. These pathways can promote hypertrophy and combat atrophy in animal models of disorders including muscular dystrophy, agerelated atrophy, denervation injury, disuse atrophy, cancer cachexia, and sepsis. cAMP also participates in muscle development and regeneration mediated by muscle precursor cells; thus, downstream signaling pathways may potentially be harnessed to promote muscle regeneration in patients with acute damage or muscular dystrophy. In this review, we summarize studies implicating cAMP signaling in skeletal muscle adaptation. We also highlight ligands that induce cAMP signaling and downstream effectors that are promising pharmacological targets. cyclic AMP; skeletal muscle; cell signaling; muscle regeneration; atrophy; protein kinase A ORIGINALLY DISCOVERED by Sutherland and Rall in liver homogenates in 1958 (218), adenosine 3=,5=-monophosphate (cyclic AMP, or cAMP) has since been intensively studied and is one of the best-characterized signaling molecules. In skeletal muscle, acute cAMP signaling has been implicated in regulation of glycogenolysis (213), contractility (32,83,84,88,138,234), sarcoplasmic calcium dynamics (58,147,184,204), and recovery from sustained contractile activity (44, 162). The net result of acute cAMP action on the order of minutes in skeletal muscle can generally be described as increased contractile force and rapid recovery of ion balance, especially during prolonged contractions. These acute changes are most pertinent to muscle contraction and energy utilization during exercise, when epinephrine is rapidly released into the circulation (92) and cAMP accumulates in muscle (72).Many studies have shown, however, that cAMP-inducing agents or genetic modification of proteins involved in cAMP signaling can also have adaptive effects on skeletal muscle by increasing myofiber size and promoting fiber-type transitions to glycolytic fibers (9,18,42,43,57,63,86,91,101,121,128,154,155,163,190,193,194,215). The prohypertrophic actions of ␤-adrenergic receptor (␤-AR) agonists and corticotropin-releasing factor recept...

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“…In addition, although ageing is associated with an increase in sympathetic nervous system activity, β-adrenoceptor density and adenylyl cyclase basal activity are also increased in gastrocnemius muscle from old rats [18]. Many studies suggest that endurance exercise training may attenuate the agerelated decline in exercise capacity [7]. Our results show that endurance training induces opposite effects to those associated with ageing in the β-adrenergic system of the rat gastrocnemius muscle.…”

Section: Discussionmentioning

confidence: 76%

“…From previous studies in the literature, a general feature of skeletal muscles from trained rats seems to be an increased or unchanged β-adrenoceptor density [2,7,17,22,29,38] accompanied by an increased or unchanged functional activity of adenylyl cyclase dependent on fibre type [2,6,17,29]. All radioligand-binding studies have failed to detect any alteration in the affinity of β-adrenoceptors in exercised animals [2,7,17,22,29,38].…”

Section: Discussionmentioning

confidence: 88%

“…These differences may be related to the fractionation procedure used for membrane preparation. Type I, oxidative muscles such as the soleus have a higher β-adrenoceptor density than that of type II or mixed, glycolytic muscles such as the gastrocnemius (approximately 6% type I and 94% type II fibres) [2,7,29,38]. Alterations in the relative fibre-type composition do not appear to explain the downregulation of the rat gastrocnemius β-adrenoceptor due to training because the type IIb to type IIa/IIx transition is the most commonly reported fibre-type change with exercise [10].…”

Section: Discussionmentioning

confidence: 99%

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Adaptations of the β-adrenoceptor-adenylyl cyclase system in rat skeletal muscle to endurance physical training

Nieto

Díaz‐Laviada

Malpartida

et al. 1997

Pfl�gers Archiv European Journal of Physiology

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beta-Adrenergic mechanisms may be important in the adaptation of skeletal muscle to endurance training. beta-Adrenergic signal transduction was examined in the gastrocnemius muscle of rats submitted to a progressive, 12-week treadmill running program and compared with sedentary controls. beta-Adrenoceptor density was significantly lower in exercised rats than in controls. The affinity constant for [125I]-(-) iodocyanopindolol binding was not different among the various groups. Adenosine cyclic monophosphate formation was significantly decreased in trained animals when isoproterenol plus guanosine triphosphate or forskolin plus Mn2+ were used to stimulate adenylyl cyclase. Immunoblot analyses revealed that the amount of the alpha-subunit of stimulatory guanine nucleotide-binding protein (Gs,alpha), both the small and the large isoforms, also decreased with physical exercise. Thus, the present report shows that endurance training results in alterations in beta-adrenergic receptor density, adenylyl cyclase activity and Gs protein level in rat gastrocnemius muscle.

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Effect of Contractile Activity on Rat Skeletal Muscle -Adrenoceptor Properties

Cited by 15 publications

References 5 publications

The rainbow trout skeletal muscle β-adrenergic system: characterization and signaling

The rainbow trout skeletal muscle β-adrenergic system: characterization and signaling

cAMP signaling in skeletal muscle adaptation: hypertrophy, metabolism, and regeneration

Adaptations of the β-adrenoceptor-adenylyl cyclase system in rat skeletal muscle to endurance physical training

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