Enhancement of hybrid-fiber types in rat soleus muscle after clenbuterol administration during hindlimb unloading

2004 ◽  
Vol 82 (5) ◽  
pp. 311-318 ◽  
Author(s):  
F Picquet ◽  
L De-Doncker ◽  
M Falempin
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Myosin Heavy Chain Isoforms ◽  
Hindlimb Unloading ◽  
Fiber Types ◽  
Myosin Isoforms ◽  
Fast Myosin ◽  
Contractile Parameters ◽  
Fast Myosin Heavy Chain

Our objective was to determine the effects of a clenbuterol (CB) treatment orally administered (2 mg per kg) to rats submitted to 14 days of hindlimb unloading (HU). The morphological and the contractile properties as well as the myosin heavy chain isoforms contained in each fiber type were determined in whole soleus muscles. As classically described after HU, a decrease in muscle wet weight and in body mass associated with a loss of muscular force, an evolution of the contractile parameters towards those of a fast muscle type, and the emergence of fast myosin heavy chain isoforms were observed. The CB treatment in the HU rats helped reduce the decrease in 1) muscle and body weights, 2) force and 3) the proportion of slow fibers, without preventing the emergence of fast myosin isoforms. Clenbuterol induced a complex remodelling of the muscle typing promoting the combination of both slow and fast myosin isoforms within one fiber. To conclude, our data demonstrate that CB administration partially counteracts the effects produced by HU, and they allow us to anticipate advances in the treatment of muscular atrophy.Key words: β2 agonist, clenbuterol, soleus, contractile parameters, myosin, immunohistochemistry, simulated microgravity, countermeasure.

scholarly journals Slow and fast myosin heavy chain content defines three types of myotubes in early muscle cell cultures.

1985 ◽  
Vol 101 (5) ◽  
pp. 1643-1650 ◽  
Author(s):  
J B Miller ◽  
M T Crow ◽  
F E Stockdale
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Pectoral Muscle ◽  
Myosin Heavy Chain Isoforms ◽  
Fiber Formation ◽  
Single Type ◽  
Fast Myosin ◽  
Slow Myosin Heavy Chain ◽  
Fast Myosin Heavy Chain ◽  
Different Populations

We prepared monoclonal antibodies specific for fast or slow classes of myosin heavy chain isoforms in the chicken and used them to probe myosin expression in cultures of myotubes derived from embryonic chicken myoblasts. Myosin heavy chain expression was assayed by gel electrophoresis and immunoblotting of extracted myosin and by immunostaining of cultures of myotubes. Myotubes that formed from embryonic day 5-6 pectoral myoblasts synthesized both a fast and a slow class of myosin heavy chain, which were electrophoretically and immunologically distinct, but only the fast class of myosin heavy chain was synthesized by myotubes that formed in cultures of embryonic day 8 or older myoblasts. Furthermore, three types of myotubes formed in cultures of embryonic day 5-6 myoblasts: one that contained only a fast myosin heavy chain, a second that contained only a slow myosin heavy chain, and a third that contained both a fast and a slow heavy chain. Myotubes that formed in cultures of embryonic day 8 or older myoblasts, however, were of a single type that synthesized only a fast class of myosin heavy chain. Regardless of whether myoblasts from embryonic day 6 pectoral muscle were cultured alone or mixed with an equal number of myoblasts from embryonic day 12 muscle, the number of myotubes that formed and contained a slow class of myosin was the same. These results demonstrate that the slow class of myosin heavy chain can be synthesized by myotubes formed in cell culture, and that three types of myotubes form in culture from pectoral muscle myoblasts that are isolated early in development, but only one type of myotube forms from older myoblasts; and they suggest that muscle fiber formation probably depends upon different populations of myoblasts that co-exist and remain distinct during myogenesis.

Enzymatic plasticity of medial gastrocnemius fibers in the adult chronic spinal cat

1990 ◽  
Vol 259 (3) ◽  
pp. C507-C514 ◽  
Author(s):  
B. Jiang ◽  
R. R. Roy ◽  
V. R. Edgerton
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Motor Units ◽  
Glycolytic Enzyme ◽  
Medial Gastrocnemius ◽  
Fiber Types ◽  
Cross Sectional ◽  
Fast Myosin ◽  
Weight Support

The metabolic plasticity of single fibers in adult cat medial gastrocnemius (MG) 6 mo after complete spinal cord transection (Sp) at T12-T13 was studied. Some Sp cats were trained to weight support (Sp-WS) 30 min/day beginning 1 mo posttransection. Cross-sectional area, succinate dehydrogenase (SDH), alpha-glycerophosphate dehydrogenase (GPD), and myofibrillar adenosinetriphosphatase (ATPase) activities were determined in fibers identified in frozen serial sections. Fibers were categorized as light or dark based on myosin ATPase staining, alkaline preincubation. The percentage of dark ATPase fibers was higher in Sp and Sp-WS (approximately 85%) than in control (approximately 60%). All dark ATPase fibers reacted positively to a fast myosin heavy chain monoclonal antibody. In both spinal groups, a higher percentage of dark ATPase fibers reacted to both fast and slow myosin heavy chain antibodies than in controls. Neither Sp nor Sp-WS cats showed fiber atrophy. Compared with control, SDH activity was decreased in both fiber types of Sp cats. Daily weight-support training ameliorated this adaptation. There were no differences among the three groups in mean GPD and ATPase activities for either fiber type. There was a slight tendency, however, for spinal cats to have higher GPD and ATPase activities (independent of type) than control, probably reflecting the larger proportion of dark ATPase fibers in these cats. These observations indicate that 6 mo after spinalization in adult cats, some of the fibers of a fast muscle became "faster" and developed oxidative and glycolytic enzyme profiles that normally are exhibited in fast fatigable motor units.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for three adult fast myosin heavy chain isoforms in type II skeletal muscle fibers in pigs.

1998 ◽  
Vol 76 (6) ◽  
pp. 1584 ◽  
Author(s):  
L Lefaucheur ◽  
R K Hoffman ◽  
D E Gerrard ◽  
C S Okamura ◽  
N Rubinstein ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Muscle Fibers ◽  
Myosin Heavy Chain Isoforms ◽  
Type Ii ◽  
Fast Myosin ◽  
Skeletal Muscle Fibers ◽  
Fast Myosin Heavy Chain

scholarly journals Myosin heavy-chain isoforms in the flight and leg muscles of hummingbirds and zebra finches

2014 ◽  
Vol 306 (11) ◽  
pp. R845-R851 ◽  
Author(s):  
Brandy P. Velten ◽  
Kenneth C. Welch
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Fiber Type ◽  
Myosin Heavy Chain Isoforms ◽  
Contractile Properties ◽  
Morphological Properties ◽  
Fiber Types ◽  
Zebra Finches ◽  
Leg Muscles ◽  
Flight Muscles

Myosin heavy chain (MHC) isoform complement is intimately related to a muscle's contractile properties, yet relatively little is known about avian MHC isoforms or how they may vary with fiber type and/or the contractile properties of a muscle. The rapid shortening of muscles necessary to power flight at the high wingbeat frequencies of ruby-throated hummingbirds and zebra finches (25–60 Hz), along with the varied morphology and use of the hummingbird hindlimb, provides a unique opportunity to understand how contractile and morphological properties of avian muscle may be reflected in MHC expression. Isoforms of the hummingbird and zebra finch flight and hindlimb muscles were electrophoretically separated and compared with those of other avian species representing different contractile properties and fiber types. The flight muscles of the study species operate at drastically different contraction rates and are composed of different histochemically defined fiber types, yet each exhibited the same, single MHC isoform corresponding to the chicken adult fast isoform. Thus, despite quantitative differences in the contractile demands of flight muscles across species, this isoform appears necessary for meeting the performance demands of avian powered flight. Variation in flight muscle contractile performance across species may be due to differences in the structural composition of this conserved isoform and/or variation within other mechanically linked proteins. The leg muscles were more varied in their MHC isoform composition across both muscles and species. The disparity in hindlimb MHC expression between hummingbirds and the other species highlights previously observed differences in fiber type composition and thrust production during take-off.

scholarly journals Distribution of fast myosin heavy chain isoforms in thick filaments of developing chicken pectoral muscle.

1989 ◽  
Vol 108 (2) ◽  
pp. 533-542 ◽  
Author(s):  
L D Taylor ◽  
E Bandman
Keyword(s):  
Monoclonal Antibodies ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Specific Antibody ◽  
Pectoral Muscle ◽  
Myosin Isoforms ◽  
Stages Of Development ◽  
Fast Myosin ◽  
Thick Filaments ◽  
Fast Myosin Heavy Chain

Colloidal gold-conjugated monoclonal antibodies were prepared to stage-specific fast myosin heavy chain (MHC) isoforms of developing chicken pectoralis major (PM). Native thick filaments from different stages of development were reacted with these antibodies and examined in the electron microscope to determine their myosin isoform composition. Filaments prepared from 12-d embryo, 10-d chick, and 1-yr chicken muscle specifically reacted with the embryonic (EB165), neonatal (2E9), and adult (AB8) antimyosin gold-conjugated monoclonal antibodies, respectively. The myosin isoform composition was more complex in thick filaments from stages of pectoral muscle where more than one isoform was simultaneously expressed. In 19-d embryo muscle where both embryonic and neonatal isoforms were present, three classes of filaments were found. One class of filaments reacted only with the embryonic antibody, a second class reacted only with the neonatal-specific antibody, and a third class of filaments were decorated by both antibodies. Similar results were obtained with filaments prepared from 44-d chicken PM where the neonatal and adult fast MHCs were expressed. These observations demonstrate that two myosin isoforms can exist in an individual thick filament in vivo. Immunoelectron microscopy was also used to determine the specific distribution of different fast MHC isoforms within individual filaments from different stages of development. The anti-embryonic and anti-adult antibodies uniformly decorated both homogeneous and heterogeneous thick filaments. The neonatal specific antibody uniformly decorated homogeneous filaments; however, it preferentially decorated the center of heterogeneous filaments. These observations suggest that neonatal MHC may play a specific role in fibrillogenesis.

The relationship between slow and fast myosin heavy chain content, calpastatin and meat tenderness in different ovine skeletal muscles

Meat Science ◽  
2005 ◽  
Vol 69 (1) ◽  
pp. 17-25 ◽  
Author(s):  
A.Q. Sazili ◽  
T. Parr ◽  
P.L. Sensky ◽  
S.W. Jones ◽  
R.G. Bardsley ◽  
...  
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Skeletal Muscles ◽  
Meat Tenderness ◽  
Fast Myosin ◽  
Fast Myosin Heavy Chain ◽  
The Relationship
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