scholarly journals Spaceflight effects on single skeletal muscle fiber function in the rhesus monkey

2000 ◽  
Vol 279 (5) ◽  
pp. R1546-R1557 ◽  
Author(s):  
Robert H. Fitts ◽  
Dominique Desplanches ◽  
Janell G. Romatowski ◽  
Jeffrey J. Widrick
Keyword(s):  
Rhesus Monkey ◽  
Peak Power ◽  
Fiber Diameter ◽  
Fiber Type ◽  
Peak Force ◽  
Medial Gastrocnemius ◽  
Type I ◽  
Type Ii ◽  
Fast Twitch ◽  
Type Ii Fibers

The purpose of this investigation was to understand how 14 days of weightlessness alters the cellular properties of individual slow- and fast-twitch muscle fibers in the rhesus monkey. The diameter of the soleus (Sol) type I, medial gastrocnemius (MG) type I, and MG type II fibers from the vivarium controls averaged 60 ± 1, 46 ± 2, and 59 ± 2 μm, respectively. Both a control 1-G capsule sit (CS) and spaceflight (SF) significantly reduced the Sol type I fiber diameter (20 and 13%, respectively) and peak force, with the latter declining from 0.48 ± 0.01 to 0.31 ± 0.02 (CS group) and 0.32 ± 0.01 mN (SF group). When the peak force was expressed as kiloNewtons per square meter (kN/m2), only the SF group showed a significant decline. This group also showed a significant 15% drop in peak fiber stiffness that suggests that fewer cross bridges were contracting in parallel. In the MG, SF but not CS depressed the type I fiber diameter and force. Additionally, SF significantly depressed absolute (mN) and relative (kN/m2) force in the fast-twitch MG fibers by 30% and 28%, respectively. The Ca2+ sensitivity of the type I fiber (Sol and MG) was significantly reduced by growth but unaltered by SF. Flight had no significant effect on the mean maximal fiber shortening velocity in any fiber type or muscle. The post-SF Sol type I fibers showed a reduced peak power and, at peak power, an elevated velocity and decreased force. In conclusion, CS and SF caused atrophy and a reduced force and power in the Sol type I fiber. However, only SF elicited atrophy and reduced force (mN) in the MG type I fiber and a decline in relative force (kN/m2) in the Sol type I and MG type II fibers.

scholarly journals Velocity, force, power, and Ca2+ sensitivity of fast and slow monkey skeletal muscle fibers

1998 ◽  
Vol 84 (5) ◽  
pp. 1776-1787 ◽  
Author(s):  
Robert H. Fitts ◽  
Sue C. Bodine ◽  
Janell G. Romatowski ◽  
Jeffrey J. Widrick
Keyword(s):  
Peak Power ◽  
Fiber Type ◽  
Medial Gastrocnemius ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Shortening Velocity ◽  
Hybrid Fibers ◽  
Slow Type ◽  
Type Ii Fibers

In this study, we determined the contractile properties of single chemically skinned fibers prepared from the medial gastrocnemius (MG) and soleus (Sol) muscles of adult male rhesus monkeys and assessed the effects of the spaceflight living facility known as the experiment support primate facility (ESOP). Muscle biopsies were obtained 4 wk before and immediately after an 18-day ESOP sit, and fiber type was determined by immunohistochemical techniques. The MG slow type I fiber was significantly smaller than the MG type II, Sol type I, and Sol type II fibers. The ESOP sit caused a significant reduction in the diameter of type I and type I/II (hybrid) fibers of Sol and MG type II and hybrid fibers but no shift in fiber type distribution. Single-fiber peak force (mN and kN/m2) was similar between fiber types and was not significantly different from values previously reported for other species. The ESOP sit significantly reduced the force (mN) of Sol type I and MG type II fibers. This decline was entirely explained by the atrophy of these fiber types because the force per cross-sectional area (kN/m2) was not altered. Peak power of Sol and MG fast type II fiber was 5 and 8.5 times that of slow type I fiber, respectively. The ESOP sit reduced peak power by 25 and 18% in Sol type I and MG type II fibers, respectively, and, for the former fiber type, shifted the force-pCa relationship to the right, increasing the Ca2+ activation threshold and the free Ca2+concentration, eliciting half-maximal activation. The ESOP sit had no effect on the maximal shortening velocity ( V o) of any fiber type. V o of the hybrid fibers was only slightly higher than that of slow type I fibers. This result supports the hypothesis that in hybrid fibers the slow myosin heavy chain would be expected to have a disproportionately greater influence on V o.

scholarly journals Denervation and reinnervation of fast and slow muscles. A histochemical study in rats.

1975 ◽  
Vol 23 (11) ◽  
pp. 808-827 ◽  
Author(s):  
M M Jaweed ◽  
G J Herbison ◽  
J F Ditunno
Keyword(s):  
Fiber Diameter ◽  
Histochemical Study ◽  
Fiber Type ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Type I Fibers ◽  
Type Ii Fibers ◽  
Fast Muscles ◽  
Slow And Fast Muscles

A histochemical study, using myosin-adenosine triphosphatase activity at pH 9.4, was conducted in soleus and plantaris muscles of adult rats, after bilateral crushing of the sciatic nerve at the sciatic notch. The changes in fiber diameter and per cent composition of type I and type II fibers plus muscle weights were evaluated along the course of denervation-reinnervation curve at 1, 2, 3, 4 and 6 weeks postnerve crush. The study revealed that in the early denervation phase (up to 2 weeks postcrush) both the slow and fast muscles, soleus and plantaris, resepctively, atrophied similarly in muscle mass. Soleus increased in the number of type II fibers, which may be attributed to "disuse" effect. During the same period, the type I fibers of soleus atrophied as much or slightly more than the type II fibers; whereas the type II fibers of plantaris atrophied significantly more than the type I fibers, reflecting that the process of denervation, in its early stages, may affect the two fiber types differentially in the slow and fast muscles. It was deduced that the type I fibers of plantaris may be essentially different in the slow (soleus) and fast (plantaris) muscles under study. The onset of reinnervation, as determined by the increase in muscle weight and fiber diameter of the major fiber type, occurred in soleus and plantaris at 2 and 3 weeks postcrush, respectively, which confirms the earlier hypotheses that the slow muscles are reinnervated sooner than the fast muscles. It is suggested that the reinnervation of muscle after crush injury may be specific to the muscle type or its predominant fiber type.

Effect of corticosteroids on diaphragm fatigue, SDH activity, and muscle fiber size

1992 ◽  
Vol 72 (1) ◽  
pp. 293-301 ◽  
Author(s):  
M. I. Lewis ◽  
S. A. Monn ◽  
G. C. Sieck
Keyword(s):  
Fatigue Resistance ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Processing System ◽  
Medial Gastrocnemius ◽  
Type I ◽  
Type Ii ◽  
Cross Sectional ◽  
Type Ii Fibers

The influence of dexamethasone on diaphragm (DIA) fatigue, oxidative capacity, and fiber cross-sectional areas (CSA) was determined in growing hamsters. One group received dexamethasone by daily subcutaneous injection for 21 days (D animals), while pair-weight (P) and free-eating controls (CTL) received saline subcutaneously. Isometric contractile properties of the DIA were determined in vitro by supramaximal direct muscle stimulation in the presence of curare. DIA fatigue resistance was determined through repetitive stimulation at 40 pulses/s for 2 min. A computer-based image-processing system was used to histochemically determine muscle fiber-type proportions, CSA, and succinate dehydrogenase activities. The medial gastrocnemius muscle (MG) was used as a limb muscle control, with histochemical studies being performed on both the superficial (s) and deep/red (r) portions. Dexamethasone markedly attenuated the normal increment in body weight over the 3-wk period. DIA fatigue resistance was significantly reduced in the D compared with CTL and P animals. Dexamethasone had no effect on fiber-type proportions of the DIA or MGr (MGs contained only type II fibers). In the DIA, the CSA of type II fibers was reduced 33% in D and 18.5% in P animals compared with CTL. Although no significant atrophy was noted in the type I DIA fibers of either D or P animals, a trend toward significance was noted in D animals compared with CTL. In the MGs, the CSA of type II fibers was reduced 33% in D and 16.5% in P animals compared with CTL. Significant atrophy of type I and II fibers of the MGr was noted in D animals compared with CTL (33.8 and 35% reductions, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Muscle Changes in Lambs with Surgically Created Scoliosis Produced in Utero

1978 ◽  
Vol 5 (3) ◽  
pp. 283-287 ◽  
Author(s):  
G.M. Kent ◽  
W. Zingg ◽  
D. Armstrong
Keyword(s):  
Musculoskeletal Diseases ◽  
Fiber Type ◽  
Surgical Techniques ◽  
Spinal Curvature ◽  
Surgical Trauma ◽  
Developmental Defect ◽  
Type I ◽  
Type Ii ◽  
Muscle Changes ◽  
Type Ii Fibers

SUMMARY:Spinal curves may be produced in fetal lambs with three surgical techniques. These procedures vary from mere exposure of the costo-vertebral junction of three ribs through a paravertebral incision, to resection of the head and part of the adjacent shaft of three ribs. The fetal age varies from forty-nine to seventy-three days. The degree of curvature present at birth seems to increase in severity with decreasing fetal age at the time of surgery, but the type of surgical procedure does not appear to influence the severity of the curve, suggesting that the mechanical presence of the ribs does not prevent the development of scoliosis in these animals.Histological studies of the m. longissimus dorsi at the apices of the curves reveal two main types of abnormality in the muscle fibers. Both Type I and Type II fibers were significantly reduced in size in the biopsies taken from the side on which the surgery was performed, and there was marked alteration in the proportion of one fiber type to the other in most biopsies taken from both operated sides when compared with biopsies from unoperated twin animals.The fetal age and amount of surgical trauma appeared to play no role in the degree of muscle alteration, suggesting that even minimal surgical trauma to the paraspinal region at any fetal age between 49–73 days is sufficient to produce significant muscle fiber abnormality and spinal curvature.A parallel is drawn between these muscle findings and those in a number of human musculoskeletal diseases, and suggests the possibility of a developmental defect in the pathogenesis of these diseases.

The deleterious effects of bed rest on human skeletal muscle fibers are exacerbated by hypercortisolemia and ameliorated by dietary supplementation

2007 ◽  
Vol 293 (1) ◽  
pp. C313-C320 ◽  
Author(s):  
R. H. Fitts ◽  
J. G. Romatowski ◽  
J. R. Peters ◽  
D. Paddon-Jones ◽  
R. R. Wolfe ◽  
...  
Keyword(s):  
Peak Power ◽  
Vastus Lateralis ◽  
Sodium Succinate ◽  
Muscle Fibers ◽  
Caloric Intake ◽  
Bed Rest ◽  
Essential Amino Acids ◽  
Peak Force ◽  
Type I ◽  
Type Ii

Prolonged inactivity associated with bed rest in a clinical setting or spaceflight is frequently associated with hypercortisolemia and inadequate caloric intake. Here, we determined the effect of 28 days of bed rest (BR); bed rest plus hypercortisolemia (BRHC); and bed rest plus essential amino acid (AA) and carbohydrate (CHO) supplement (BRAA) on the size and function of single slow- and fast-twitch muscle fibers. Supplementing meals, the BRAA group consumed 16.5 g essential amino acids and 30 g sucrose at 1100, 1600, and 2100 h, and the BRHC subjects received 5 daily doses of 10–15 mg of oral hydrocortisone sodium succinate throughout bed rest. Bed rest induced atrophy and loss of force (mN) and power (μN·FL·s−1) in single fibers was exacerbated by hypercortisolemia where soleus peak force declined by 23% in the type I fiber from a prevalue of 0.78 ± 0.02 to 0.60 ± 0.02 mN post bed rest (compared to a 7% decline with bed rest alone) and 27% in the type II fiber (1.10 ± 0.08 vs. 0.81 ± 0.05 mN). In the BRHC group, peak power dropped by 19, 15, and 11% in the soleus type I, and vastus lateralis (VL) type I and II fibers, respectively. The AA/CHO supplement protected against the bed rest-induced loss of peak force in the type I soleus and peak power in the VL type II fibers. These results provide evidence that an AA/CHO supplement might serve as a successful countermeasure to help preserve muscle function during periods of relative inactivity.

scholarly journals Satellite cell content is specifically reduced in type II skeletal muscle fibers in the elderly

2007 ◽  
Vol 292 (1) ◽  
pp. E151-E157 ◽  
Author(s):  
Lex B. Verdijk ◽  
René Koopman ◽  
Gert Schaart ◽  
Kenneth Meijer ◽  
Hans H. C. M. Savelberg ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Fiber Type ◽  
The Elderly ◽  
Type I ◽  
Type Ii ◽  
Fiber Area ◽  
Muscle Fiber Atrophy ◽  
Fiber Atrophy ◽  
Type Ii Fibers

Satellite cells (SC) are essential for skeletal muscle growth and repair. Because sarcopenia is associated with type II muscle fiber atrophy, we hypothesized that SC content is specifically reduced in the type II fibers in the elderly. A total of eight elderly (E; 76 ± 1 yr) and eight young (Y; 20 ± 1 yr) healthy males were selected. Muscle biopsies were collected from the vastus lateralis in both legs. ATPase staining and a pax7-antibody were used to determine fiber type-specific SC content (i.e., pax7-positive SC) on serial muscle cross sections. In contrast to the type I fibers, the proportion and mean cross-sectional area of the type II fibers were substantially reduced in E vs. Y. The number of SC per type I fiber was similar in E and Y. However, the number of SC per type II fiber was substantially lower in E vs. Y (0.044 ± 0.003 vs. 0.080 ± 0.007; P < 0.01). In addition, in the type II fibers, the number of SC relative to the total number of nuclei and the number of SC per fiber area were also significantly lower in E. This study is the first to show type II fiber atrophy in the elderly to be associated with a fiber type-specific decline in SC content. The latter is evident when SC content is expressed per fiber or per fiber area. The decline in SC content might be an important factor in the etiology of type II muscle fiber atrophy, which accompanies the loss of skeletal muscle with aging.

scholarly journals Functional and structural adaptations of skeletal muscle to microgravity

2001 ◽  
Vol 204 (18) ◽  
pp. 3201-3208 ◽  
Author(s):  
Robert H. Fitts ◽  
Danny R. Riley ◽  
Jeffrey J. Widrick
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Peak Force ◽  
Type I ◽  
Type Ii ◽  
Shortening Velocity ◽  
Slow Type ◽  
Fiber Atrophy ◽  
Type I Fibers ◽  
Type Ii Fibers

SUMMARY Our purpose is to summarize the major effects of space travel on skeletal muscle with particular emphasis on factors that alter function. The primary deleterious changes are muscle atrophy and the associated decline in peak force and power. Studies on both rats and humans demonstrate a rapid loss of cell mass with microgravity. In rats, a reduction in muscle mass of up to 37% was observed within 1 week. For both species, the antigravity soleus muscle showed greater atrophy than the fast-twitch gastrocnemius. However, in the rat, the slow type I fibers atrophied more than the fast type II fibers, while in humans, the fast type II fibers were at least as susceptible to space-induced atrophy as the slow fiber type. Space flight also resulted in a significant decline in peak force. For example, the maximal voluntary contraction of the human plantar flexor muscles declined by 20–48% following 6 months in space, while a 21% decline in the peak force of the soleus type I fibers was observed after a 17-day shuttle flight. The reduced force can be attributed both to muscle atrophy and to a selective loss of contractile protein. The former was the primary cause because, when force was expressed per cross-sectional area (kNm−2), the human fast type II and slow type I fibers of the soleus showed no change and a 4% decrease in force, respectively. Microgravity has been shown to increase the shortening velocity of the plantar flexors. This increase can be attributed both to an elevated maximal shortening velocity (V0) of the individual slow and fast fibers and to an increased expression of fibers containing fast myosin. Although the cause of the former is unknown, it might result from the selective loss of the thin filament actin and an associated decline in the internal drag during cross-bridge cycling. Despite the increase in fiber V0, peak power of the slow type I fiber was reduced following space flight. The decreased power was a direct result of the reduced force caused by the fiber atrophy. In addition to fiber atrophy and the loss of force and power, weightlessness reduces the ability of the slow soleus to oxidize fats and increases the utilization of muscle glycogen, at least in rats. This substrate change leads to an increased rate of fatigue. Finally, with return to the 1g environment of earth, rat studies have shown an increased occurrence of eccentric contraction-induced fiber damage. The damage occurs with re-loading and not in-flight, but the etiology has not been established.

Fiber type and temperature dependence of inorganic phosphate: implications for fatigue

2004 ◽  
Vol 287 (3) ◽  
pp. C673-C681 ◽  
Author(s):  
E. P. Debold ◽  
H. Dave ◽  
R. H. Fitts
Keyword(s):  
Contractile Function ◽  
Contractile Activity ◽  
Isometric Force ◽  
Fiber Type ◽  
Type I ◽  
Type Ii ◽  
Shortening Velocity ◽  
Single Fibers ◽  
Type I Fibers ◽  
Type Ii Fibers

Elevated levels of Pi are thought to cause a substantial proportion of the loss in muscular force and power output during fatigue from intense contractile activity. However, support for this hypothesis is based, in part, on data from skinned single fibers obtained at low temperatures (≤15°C). The effect of high (30 mM) Pi concentration on the contractile function of chemically skinned single fibers was examined at both low (15°C) and high (30°C) temperatures using fibers isolated from rat soleus (type I fibers) and gastrocnemius (type II fibers) muscles. Elevating Pi from 0 to 30 mM at saturating free Ca2+ levels depressed maximum isometric force (Po) by 54% at 15°C and by 19% at 30°C ( P < 0.05; significant interaction) in type I fibers. Similarly, the Po of type II fibers was significantly more sensitive to high levels of Pi at the lower (50% decrease) vs. higher temperature (5% decrease). The maximal shortening velocity of both type I and type II fibers was not significantly affected by elevated Pi at either temperature. However, peak fiber power was depressed by 49% at 15°C but by only 16% at 30°C in type I fibers. Similarly, in type II fibers, peak power was depressed by 40 and 18% at 15 and 30°C, respectively. These data suggest that near physiological temperatures and at saturating levels of intracellular Ca2+, elevated levels of Pi contribute less to fatigue than might be inferred from data obtained at lower temperatures.

The Effects of Non-Weight Bearing on Skeletal Muscle in Older Rats: an Interrupted Bout versus an Uninterrupted Bout

2004 ◽  
Vol 5 (3) ◽  
pp. 195-202 ◽  
Author(s):  
Alissa Guildner Gehrke ◽  
Margaret Sheie Krull ◽  
Robin Shotwell McDonald ◽  
Tracy Sparby ◽  
Jessica Thoele ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Fiber Type ◽  
Weight Bearing ◽  
Cross Sectional Area ◽  
Type I ◽  
Type Ii ◽  
Sectional Area ◽  
Cross Sectional ◽  
Age Related ◽  
Type Ii Fibers

Age-related changes in skeletal muscle, in combination with bed rest, may result in a poorer rehabilitation potential for an elderly patient. The purpose of this study was to determine the effects of non-weight bearing (hind limb unweighting [HU]) on the soleus and extensor digitorum longus (EDL) in older rats. Two non-weight bearing conditions were used: an uninterrupted bout of HU and an interrupted bout of HU. Twenty-one rats were randomly placed into 1 of 3 groups: control, interrupted HU (2 phases of 7 days of HU, separated by a 4-day weight-bearing phase) and an uninterrupted HU (18 uninterrupted days of HU). Following non-weight bearing, the soleus and EDL muscles were removed. Fiber type identification was performed by myofibrillar ATPase and cross-sectional area was determined. The findings suggest that any period of non-weight bearing leads to a decrease in muscle wet weight (19%-45%). Both type I and type II fibers of the soleus showed atrophy (decrease in cross-sectional area, 35%-44%) with an uninterrupted bout of non-weight bearing. Only the type II fibers of the soleus showed recovery with an interrupted bout of weight bearing. In the EDL, type II fibers were more affected by an uninterrupted bout of non-weight bearing (15% decrease in fiber size) compared to the type I fibers. EDL type II fibers showed more atrophy with interrupted bouts of non-weight bearing than with a single bout (a 40% compared to a 15% decrease). This study shows that initial weight bearing after an episode of non-weight bearing may be damaging to type II fibers of the EDL.

Muscle Fiber Type Distribution in the Normal Human Levator Veli Palatini Muscle

1998 ◽  
Vol 35 (5) ◽  
pp. 419-424 ◽  
Author(s):  
Jerald B. Moon ◽  
Sue Ann Thompson ◽  
Elise Jaeckel ◽  
John W. Canady
Keyword(s):  
Muscle Tissue ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Type I ◽  
Type Ii ◽  
Type Distribution ◽  
Levator Veli Palatini ◽  
Fiber Type Distribution ◽  
Type I Fibers ◽  
Type Ii Fibers

Objective This study examined the muscle fiber type distribution within the normal adult levator veli palatini muscle. Methods Levator veli palatini muscle tissue was harvested from the palates of 12 (seven female, five male) adult noncleft cadavers. Adjacent sections were stained for adenosine triphosphatase at pH 10.4 or 4.2. After mounting, magnifying, and photographing, Type I versus Type II fiber types were differentiated by the intensity of, or by the inhibition of, staining of matched fibers at each pH level. Type I fibers stained light at pH 10.4 and dark at pH 4.2, while Type II fibers stained light at pH 4.2 and dark at pH 10.4. Main outcome Measures The number of fibers counted for each specimen ranged from 60 to 616. The numbers of Type I and Type II stained fibers appearing in each muscle tissue sample were determined and expressed as a percentage of the total number of fibers identified. A few identified fibers could not be labelled as either Type I or Type II. Results The overall proportion of Type I fibers, averaged across all specimens, was 59.8%. Male specimens had 67.4% Type I fibers and 31.8% Type II fibers, while female specimens had 54.4% Type I fibers and 44.4% Type II fibers. Conclusions Observed fiber type distributions were similar to those reported for other articulatory muscles, but differed slightly from previously reported distributions for normal levator veli palatini. The distributions observed in this study provide a baseline against which to relate fiber type data from the levator veli palatini of cleft palates to the functional status of the velopharyngeal mechanism.

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