scholarly journals Changes of Contractile Properties of Extensor Digitorum Longus in Response to Creatine-Analogue Administration and/or Hindlimb Suspension in Rats.

1995 ◽  
Vol 45 (6) ◽  
pp. 979-989 ◽  
Author(s):  
T. WAKATSUKI ◽  
Y. OHIRA ◽  
K. NAKAMURA ◽  
T. ASAKURA ◽  
H. OHNO ◽  
...  
Keyword(s):  
Extensor Digitorum Longus ◽  
Contractile Properties ◽  
Extensor Digitorum ◽  
Hindlimb Suspension

Spaceflight on STS-48 and earth-based unweighting produce similar effects on skeletal muscle of young rats

1993 ◽  
Vol 74 (5) ◽  
pp. 2161-2165 ◽  
Author(s):  
M. E. Tischler ◽  
E. J. Henriksen ◽  
K. A. Munoz ◽  
C. S. Stump ◽  
C. R. Woodman ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Extensor Digitorum Longus ◽  
Space Shuttle ◽  
Weight Bearing ◽  
Similar Rate ◽  
Extensor Digitorum ◽  
Hindlimb Suspension ◽  
Albino Rats ◽  
Sprague Dawley ◽  
Ambient Temperatures

Our knowledge of the effects of unweighting on skeletal muscle of juvenile rapidly growing rats has been obtained entirely by using hindlimb-suspension models. No spaceflight data on juvenile animals are available to validate these models of simulated weightlessness. Therefore, eight 26-day-old female Sprague-Dawley albino rats were exposed to 5.4 days of weightlessness aboard the space shuttle Discovery (mission STS-48, September 1991). An asynchronous ground control experiment mimicked the flight cage condition, ambient shuttle temperatures, and mission duration for a second group of rats. A third group of animals underwent hindlimb suspension for 5.4 days at ambient temperatures. Although all groups consumed food at a similar rate, flight animals gained a greater percentage of body mass per day (P < 0.05). Mass and protein data showed weight-bearing hindlimb muscles were most affected, with atrophy of the soleus and reduced growth of the plantaris and gastrocnemius in both the flight and suspended animals. In contrast, the non-weight-bearing extensor digitorum longus and tibialis anterior muscles grew normally. Earlier suspension studies showed that the soleus develops an increased sensitivity to insulin during unweighting atrophy, particularly for the uptake of 2-[1,2–3H]deoxyglucose. Therefore, this characteristic was studied in isolated muscles within 2 h after cessation of spaceflight or suspension. Insulin increased uptake 2.5- and 2.7-fold in soleus of flight and suspended animals, respectively, whereas it increased only 1.6-fold in control animals. In contrast, the effect of insulin was similar among the three groups for the extensor digitorum longus, which provides a control for potential systemic differences in the animals.

Effects of unweighting and clenbuterol on myosin light and heavy chains in fast and slow muscles of rat

2000 ◽  
Vol 279 (5) ◽  
pp. C1558-C1563 ◽  
Author(s):  
Laurence Stevens ◽  
Carole Firinga ◽  
Bärbel Gohlsch ◽  
Bruno Bastide ◽  
Yvonne Mounier ◽  
...  
Keyword(s):  
Light Chain ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Hindlimb Suspension ◽  
Adrenergic Agonist ◽  
Heavy Chains ◽  
Fast And Slow Muscles ◽  
Induced Changes ◽  
Fast Muscles ◽  
Slow And Fast Muscles

To investigate the plasticity of slow and fast muscles undergoing slow-to-fast transition, rat soleus (SOL), gastrocnemius (GAS), and extensor digitorum longus (EDL) muscles were exposed for 14 days to 1) unweighting by hindlimb suspension (HU), or 2) treatment with the β2-adrenergic agonist clenbuterol (CB), or 3) a combination of both (HU-CB). In general, HU elicited atrophy, CB induced hypertrophy, and HU-CB partially counteracted the HU-induced atrophy. Analyses of myosin heavy (MHC) and light chain (MLC) isoforms revealed HU- and CB-induced slow-to-fast transitions in SOL (increases of MHCIIa with small amounts of MHCIId and MHCIIb) and the upregulation of the slow MHCIa isoform. The HU- and CB-induced changes in GAS consisted of increases in MHCIId and MHCIIb (“fast-to-faster transitions”). Changes in the MLC composition of SOL and GAS consisted of slow-to-fast transitions and mainly encompassed an exchange of MLC1s with MLC1f. In addition, MLC3f was elevated whenever MHCIId and MHCIIb isoforms were increased. Because the EDL is predominantly composed of type IID and IIB fibers, HU, CB, and HU-CB had no significant effect on the MHC and MLC patterns.

Effects of endurance exercise-training on single-fiber contractile properties of insulin-treated streptozotocin-induced diabetic rats

2005 ◽  
Vol 99 (2) ◽  
pp. 472-478 ◽  
Author(s):  
Otto A. Sanchez ◽  
LeAnn M. Snow ◽  
Dawn A. Lowe ◽  
Robert C. Serfass ◽  
LaDora V. Thompson
Keyword(s):  
Exercise Training ◽  
Endurance Exercise ◽  
Extensor Digitorum Longus ◽  
Diabetic Rats ◽  
Contractile Properties ◽  
Extensor Digitorum ◽  
Single Fiber ◽  
Moderate Intensity ◽  
Specific Tension ◽  
Endurance Exercise Training

The purpose of this study was to characterize the contractile properties of individual skinned muscle fibers from insulin-treated streptozotocin-induced diabetic rats after an endurance exercise training program. We hypothesized that single-fiber contractile function would decrease in the diabetic sedentary rats and that endurance exercise would preserve the function. In the study, 28 rats were assigned to either a nondiabetic sedentary, a nondiabetic exercise, a diabetic sedentary, or a diabetic exercise group. Rats in the diabetic groups received subcutaneous intermediate-lasting insulin daily. The exercise-trained rats ran on a treadmill at a moderate intensity for 60 min, five times per week. After 12 wk, the extensor digitorum longus and soleus muscles were dissected. Single-fiber diameter, Ca2+-activated peak force, specific tension, activation threshold, and pCa50 as well as the myosin heavy chain isoform expression (MHC) were determined. We found that in MHC type II fibers from extensor digitorum longus muscle, diameters were significantly smaller from diabetic sedentary rats compared with nondiabetic sedentary rats ( P < 0.001). Among the nondiabetic rats, fiber diameters were smaller with exercise ( P = 0.038). The absolute force-generating capacity of single fibers was lower in muscles from diabetic rats. There was greater specific tension (force normalized to cross-sectional area) by fibers from the rats that followed an endurance exercise program compared with sedentary. From the results, we conclude that alterations in the properties of contractile proteins are not implicated in the decrease in strength associated with diabetes and that endurance-exercise training does not prevent or increase muscle weakness in diabetic rats.

scholarly journals Chronic hindlimb suspension unloading markedly decreases turnover rates of skeletal and cardiac muscle proteins and adipose tissue triglycerides

2015 ◽  
Vol 119 (1) ◽  
pp. 16-26 ◽  
Author(s):  
Ilya R. Bederman ◽  
Nicola Lai ◽  
Jeffrey Shuster ◽  
Leigh Henderson ◽  
Steven Ewart ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Energy Balance ◽  
Energy Expenditure ◽  
Cardiac Muscle ◽  
Extensor Digitorum Longus ◽  
Extensor Digitorum ◽  
Hindlimb Suspension ◽  
Muscle Proteins ◽  
Turnover Rates ◽  
Cardiac Muscles

We previously showed that a single bolus of “doubly-labeled” water (2H218O) can be used to simultaneously determine energy expenditure and turnover rates (synthesis and degradation) of tissue-specific lipids and proteins by modeling labeling patterns of protein-bound alanine and triglyceride-bound glycerol (Bederman IR, Dufner DA, Alexander JC, Previs SF. Am J Physiol Endocrinol Metab 290: E1048–E1056, 2006). Using this novel method, we quantified changes in the whole body and tissue-specific energy balance in a rat model of simulated “microgravity” induced by hindlimb suspension unloading (HSU). After chronic HSU (3 wk), rats exhibited marked atrophy of skeletal and cardiac muscles and significant decrease in adipose tissue mass. For example, soleus muscle mass progressively decreased 11, 43, and 52%. We found similar energy expenditure between control (90 ± 3 kcal·kg−1·day−1) and hindlimb suspended (81 ± 6 kcal/kg day) animals. By comparing food intake (∼112 kcal·kg−1·day−1) and expenditure, we found that animals maintained positive calorie balance proportional to their body weight. From multicompartmental fitting of 2H-labeling patterns, we found significantly ( P < 0.005) decreased rates of synthesis (percent decrease from control: cardiac, 25.5%; soleus, 70.3%; extensor digitorum longus, 44.9%; gastrocnemius, 52.5%; and adipose tissue, 39.5%) and rates of degradation (muscles: cardiac, 9.7%; soleus, 52.0%; extensor digitorum longus, 27.8%; gastrocnemius, 37.4%; and adipose tissue, 50.2%). Overall, HSU affected growth of young rats by decreasing the turnover rates of proteins in skeletal and cardiac muscles and adipose tissue triglycerides. Specifically, we found that synthesis rates of skeletal and cardiac muscle proteins were affected to a much greater degree compared with the decrease in degradation rates, resulting in large negative balance and significant tissue loss. In contrast, we found a small decrease in adipose tissue triglyceride synthesis paired with a large decrease in degradation, resulting in smaller negative energy balance and loss of fat mass. We conclude that HSU in rats differentially affects turnover of muscle proteins vs. adipose tissue triglycerides.

Changes in isometric contractile properties of extensor digitorum longus and soleus muscles of C57BL/6J mice following denervation

1985 ◽  
Vol 63 (6) ◽  
pp. 681-686 ◽  
Author(s):  
D. M. S. Webster ◽  
B. H. Bressler
Keyword(s):  
Extensor Digitorum Longus ◽  
Marked Decrease ◽  
Age Groups ◽  
Contractile Properties ◽  
Extensor Digitorum ◽  
Contraction Time ◽  
Normal Response ◽  
Time To Peak ◽  
Generating Capacity ◽  
Wet Weight

In this study, conducted on mice of the C57BL/6J+/+ strain, we investigated the differential effects of denervation on the isometric contractile properties of the extensor digitorum longus (EDL) and soleus (SOL) muscles. The contractile properties were studied at 1, 28, 84, and 210 days following unilateral section of the sciatic nerve at 12 weeks of age. When isometric tetanus tension was expressed relative to wet weight, the denervated SOL showed an earlier and more pronounced loss in tension generating capacity than the EDL. Both the denervated SOL and EDL showed potentiation of the twitch tension at 28 days postdenervation. The time to peak twitch tension (TTP) and the time to half-relaxation (1/2RT) were prolonged by 28 days postdenervation in both muscles. This trend continued to the oldest age-groups studied in the EDL, but reached an apparent plateau in the SOL at 84 days postdenervation. In response to fatigue, the denervated SOL showed a marked decrease in resistance to fatigue at 1 day but a relatively normal response thereafter, whereas the denervated EDL showed an increase in resistance to fatigue at and beyond the 28-day period. In spite of the fact that the total contraction time of both muscles increased following denervation, the predominantly oxidative SOL remained a slower contracting muscle than the more glycolytic EDL.

scholarly journals Effects of Chronic Administration of Clenbuterol on Contractile Properties and Calcium Homeostasis in Rat Extensor Digitorum Longus Muscle

PLoS ONE ◽  
2014 ◽  
Vol 9 (6) ◽  
pp. e100281 ◽  
Author(s):  
Pascal Sirvent ◽  
Aymerick Douillard ◽  
Olivier Galbes ◽  
Christelle Ramonatxo ◽  
Guillaume Py ◽  
...  
Keyword(s):  
Calcium Homeostasis ◽  
Extensor Digitorum Longus ◽  
Chronic Administration ◽  
Extensor Digitorum Longus Muscle ◽  
Contractile Properties ◽  
Extensor Digitorum ◽  
Longus Muscle
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