Adaptations of diaphragm and medial gastrocnemius muscles to inactivity

1992 ◽  
Vol 72 (4) ◽  
pp. 1445-1453 ◽  
Author(s):  
W. Z. Zhan ◽  
G. C. Sieck
Keyword(s):  
Fiber Type ◽  
Relaxation Times ◽  
Medial Gastrocnemius ◽  
Fatigue Properties ◽  
Type I ◽  
Cross Sectional ◽  
Isometric Twitch ◽  
The Right ◽  
Type I Fibers

The effects of 2 wk of inactivity on in vitro contractile properties of diaphragm and medial gastrocnemius (MG) muscles were examined in adult hamsters. In addition, inactivity effects on fiber-type proportions and cross-sectional areas were studied. Inactivity of the right hemidiaphragm or MG muscle was induced by either tetrodotoxin (TTX) blockade of nerve impulses or denervation (DNV). Inactivity effects on diaphragm or MG were compared with corresponding sham (saline-treated or untreated control) muscles. After both TTX- and DNV-induced inactivity, isometric twitch contraction and half-relaxation times were prolonged, maximum tetanic force decreased, and fatigue resistance improved. Proportions of type I and II fibers in both diaphragm and MG were unaffected by TTX- and DNV-induced inactivity. However, in both muscles, type I fibers hypertrophied, whereas type II fibers atrophied. In diaphragm, contractile and morphometric adaptations after DNV were generally more pronounced than those induced by TTX. In addition, compared with corresponding untreated or saline-treated control groups, inactivity effects (both TTX and DNV) on MG were generally greater than those induced in diaphragm, with the exception of hypertrophy of type I fibers. We conclude that inactivity exerts differential effects on type I and II fibers in both diaphragm and MG. Yet, these morphometric adaptations cannot completely account for the adaptations in muscle contractile and fatigue properties after inactivity.

Effect of acute nutritional deprivation on diaphragm structure and function

1990 ◽  
Vol 68 (5) ◽  
pp. 1938-1944 ◽  
Author(s):  
M. I. Lewis ◽  
G. C. Sieck
Keyword(s):  
Nerve Stimulation ◽  
Muscle Fibers ◽  
Medial Gastrocnemius ◽  
Fatigue Properties ◽  
Muscle Stimulation ◽  
Type I ◽  
Cross Sectional ◽  
Nutritional Deprivation ◽  
Nerve Muscle

The influence of 90 h of acute nutritional deprivation (ND) on the cross-sectional areas of muscle fibers and the contractile and fatigue properties of the adult rat diaphragm were determined. Isometric contractile properties and fatigue resistance of the diaphragm were measured by means of an in vitro nerve-muscle strip preparation. Contractions were evoked by using phrenic nerve stimulation (left hemidiaphragm) or direct muscle stimulation (right hemidiaphragm) in the presence of curare. Acute ND resulted in a 20% reduction in body weight. No significant decrements in diaphragm or soleus weights were noted in the ND animals compared with controls (CTL), whereas the weight of the medial gastrocnemius was reduced by 20% in the ND animals. Peak twitch and tetanic tensions (normalized for the weight of the diaphragm strip) were not reduced in ND compared with CTL animals after either nerve or muscle stimulation. The fatigue index of the diaphragm was significantly reduced in ND animals only after nerve stimulation. After the fatigue test, there was rapid recovery of the additional fatigue noted with nerve stimulation. The proportions of type I and II muscle fibers of the diaphragm were similar in the CTL and ND animals. No differences in diaphragm cross-sectional areas were noted for either type I or II muscle fibers in the CTL and ND animals. It is concluded that acute ND has no effect on diaphragm contractility or morphometry and only an inconsequential influence on diaphragm fatigue.

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)

Rostrocaudal pattern of fiber-type changes in an overloaded rat ankle extensor

1991 ◽  
Vol 71 (2) ◽  
pp. 558-564 ◽  
Author(s):  
P. F. Gardiner ◽  
B. J. Jasmin ◽  
P. Corriveau
Keyword(s):  
Fiber Type ◽  
Muscle Length ◽  
Similar Degree ◽  
Complex Nature ◽  
Type I ◽  
Fiber Types ◽  
Type Ii ◽  
Cross Sectional ◽  
Hypertrophic Response ◽  
Type I Fibers

Our aim was to quantify the overload-induced hypertrophy and conversion of fiber types (type II to I) occurring in the medial head of the gastrocnemius muscle (MG). Overload of MG was induced by a bilateral tenotomy/retraction of synergists, followed by 12–18 wk of regular treadmill locomotion (2 h of walking/running per day on 3 of 4 days). We counted all type I fibers and determined type I and II mean fiber areas in eight equidistant sections taken along the length of control and overloaded MG. Increase in muscle weights (31%), as well as in total muscle cross-sectional areas (37%) and fiber areas (type I, 57%; type II, 34%), attested to a significant hypertrophic response in overloaded MG. An increase in type I fiber composition of MG from 7.0 to 11.5% occurred as a result of overload, with the greatest and only statistically significant changes (approximately 70–100%) being found in sections taken from the most rostral 45% of the muscle length. Results of analysis of sections taken from the largest muscle girth showed that it significantly underestimated the extent of fiber conversion that occurred throughout the muscle as a whole. These data obtained on the MG, which possesses a compartmentalization of fiber types, support the notion that all fiber types respond to this model with a similar degree of hypertrophy. Also, they emphasize the complex nature of the adaptive changes that occur in these types of muscles as a result of overload.

In vitro human masseter muscle hypersensitivity: a possible explanation for increase in masseter tone

1996 ◽  
Vol 80 (5) ◽  
pp. 1547-1553 ◽  
Author(s):  
P. J. Adnet ◽  
H. Reyford ◽  
B. M. Tavernier ◽  
T. Etchrivi ◽  
I. Krivosic ◽  
...  
Keyword(s):  
Masseter Muscle ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Threshold Concentration ◽  
Vastus Lateralis Muscle ◽  
Type I ◽  
Cross Sectional ◽  
Significant Difference ◽  
Maximal Tension

To determine whether a difference in fiber-type caffeine and Ca2+ sensitivities exists between human masseter and vastus lateralis skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers from 13 masseter and 18 vastus lateralis muscles. Caffeine sensitivity was defined as the threshold concentration inducing > 10% of the maximal tension obtained after the fiber was loaded with a 1.6 x 10(-2) mM Ca2+ solution for 30 s. Significant difference in the mean caffeine sensitivity was found between type I masseter fibers [2.57 +/- 1.32 (SD) mM] vs. type I (6.02 +/- 1.74 mM) and type II vastus lateralis fibers (11.25 +/- 3.13 mM). Maximal Ca(2+)-activated force per cross-sectional area was significantly different between masseter and vastus lateralis fibers. However, the Ca2+ concentration corresponding to half-maximal tension (pCa50) was not significantly different between type I masseter (pCa50 5.9 +/- 0.02) and type I vastus lateralis muscle (pCa50 6.01 +/- 0.08). These results suggest that the increase in caffeine sensitivity of masseter muscle reflects the presence of a low reactivity threshold of the sarcoplasmic reticulum.

Diaphragm muscle fatigue resistance during postnatal development

1991 ◽  
Vol 71 (2) ◽  
pp. 458-464 ◽  
Author(s):  
G. C. Sieck ◽  
M. Fournier ◽  
C. E. Blanco
Keyword(s):  
Postnatal Development ◽  
Fatigue Resistance ◽  
Muscle Fibers ◽  
Diaphragm Muscle ◽  
Fatigue Properties ◽  
Type I ◽  
Type Ii ◽  
Cross Sectional ◽  
Type I Fibers ◽  
Type Ii Fibers

postnatal development. Both twitch contraction time and half-relaxation time decreased progressively with age. Correspondingly, the force-frequency curve was shifted to the left early in development compared with adults. The ratio of peak twitch force to maximum tetanic force decreased with age. Fatigue resistance of the diaphragm was highest at birth and then progressively decreased with age. At birth, most diaphragm muscle fibers stained darkly for myofibrillar adenosinetriphosphatase after alkaline preincubation and thus would be classified histochemically as type II. During subsequent postnatal development, the proportion of type I fibers (lightly stained for adenosinetriphosphatase) increased while the number of type II fibers declined. At birth, type I fibers were larger than type II fibers. The size of both fiber types increased with age, but the increase in cross-sectional area was greater for type II fibers. On the basis of fiber type proportions and mean cross-sectional areas, type I fibers contributed 15% of total muscle mass at birth and 25% in adults. Thus postnatal changes in diaphragm contractile and fatigue properties cannot be attributed to changes in the relative contribution of histochemically classified type I and II fibers. However, the possibility that these developmental changes in diaphragm contractile and fatigue properties correlated with the varying contractile protein composition of muscle fibers was discussed.

L-carnitine combined with minimal electrical stimulation promotes type transformation of canine latissimus dorsi

1994 ◽  
Vol 76 (4) ◽  
pp. 1636-1642 ◽  
Author(s):  
M. L. Dubelaar ◽  
J. F. Glatz ◽  
Y. F. De Jong ◽  
F. H. Van der Veen ◽  
W. C. Hulsmann
Keyword(s):  
Electrical Stimulation ◽  
Latissimus Dorsi ◽  
Fiber Type ◽  
Control Period ◽  
Placebo Control ◽  
Significant Shift ◽  
Type I ◽  
The Right ◽  
Type I Fibers

In the first part of this study, in four dogs the left latissimus dorsi was equipped to perform in vivo contraction measurements and the right latissimus dorsi served as control. After a control period, the dogs received L-carnitine intravenously for 8 wk. We found that carnitine caused the percentage of type I fibers to increase from 30 to 55% in the left latissimus dorsi but no change in the right latissimus dorsi. In the left latissimus dorsi, the contraction speed (percentage ripple) decreased from 75 to 30% and cytochrome-c oxidase activity increased 1.6-fold. No changes occurred in the right latissimus dorsi. To verify these observations, we performed a second study with placebo control for 8 wk, and only the left latissimus dorsi was subjected to weekly electrical stimulation. In the carnitine-treated dogs, the stimulated muscle showed an increase in the percentage of type I fibers from 16 to 35% and the ripple decreased from 92 to 77%. These measures did not change in the placebo-treated dogs. We concluded that weekly short-term stimulation does not lead to a change in fiber type; however, carnitine combined with minimal stimulation of the muscle leads to a significant shift in muscle fiber type composition toward a muscle with an increased content of type I fibers.

Mr Relaxation Times and Fiber Type Predominance of the Psoas and Multifidus Muscle

1993 ◽  
Vol 34 (1) ◽  
pp. 16-19 ◽  
Author(s):  
R. Parkkola ◽  
A. Alanen ◽  
H. Kalimo ◽  
I. Lillsunde ◽  
M. Komu ◽  
...  
Keyword(s):  
Fiber Type ◽  
Relaxation Times ◽  
Psoas Muscle ◽  
Relative Mass ◽  
T2 Relaxation ◽  
Multifidus Muscle ◽  
Cross Sectional ◽  
Mr Relaxation

MR relaxation times, fiber composition, nonmyofiber space, water content, and fat content of human psoas and multifidus muscle samples of 10 male cadavers were studied in vitro. The T1 and T2 relaxation times of multifidus muscle were significantly longer than those of the psoas muscle. On average, type 1 fibers (slow fibers with a small cross-sectional diameter) predominated in both muscles. There was no correlation between the relative mass of type 1 or 2 fibers (fast fibers with a large cross-sectional diameter) or nonmyofiber space and the relaxation times. The quantity of fat in the muscle did not correlate with the relaxation times either.

Adaptations of the diaphragm in emphysema

1992 ◽  
Vol 72 (3) ◽  
pp. 934-943 ◽  
Author(s):  
M. I. Lewis ◽  
W. Z. Zhan ◽  
G. C. Sieck
Keyword(s):  
Muscle Fibers ◽  
Capillary Density ◽  
Histochemical Staining ◽  
Diaphragm Muscle ◽  
Fatigue Properties ◽  
Type I ◽  
Cross Sectional ◽  
Metabolic Properties ◽  
Type Ii Fibers

In adult male hamsters the influence of emphysema (EMP) on the in vitro contractile and fatigue properties and the histochemical, morphometric, and metabolic properties of muscle fibers in the costal diaphragm was determined 6 mo after the administration of either elastase or saline (controls, CTL). Isometric contractile properties were determined in vitro using supramaximal direct muscle stimulation. Optimal fiber length for force generation was significantly shorter in the EMP than in the CTL diaphragm. Maximum specific force (i.e., force per unit area) was 25% lower than CTL. Fatigue resistance was significantly improved in the EMP diaphragm compared with CTL. Diaphragm muscle fibers were classified as type I or II on the basis of histochemical staining for myofibrillar adenosinetriphosphatase after alkaline preincubation. The proportions of type I and II fibers were similar between the two groups. Cross-sectional areas of type II fibers were 30% larger in EMP than in CTL diaphragms. Succinate dehydrogenase activities of both type I and II fibers were higher in EMP than in CTL diaphragms. The number of capillaries surrounding both type I and II fibers increased with EMP, but in proportion to the hypertrophy of these fibers. Thus, capillary density (number of capillaries per fiber cross-sectional area) remained unchanged. We postulate that these contractile, morphometric, and metabolic adaptations reflect an increased activation of the diaphragm in response to the loads imposed by EMP.

scholarly journals Fiber Composition and Oxidative Capacity of Hamster Skeletal Muscle

2002 ◽  
Vol 50 (12) ◽  
pp. 1685-1692 ◽  
Author(s):  
John P. Mattson ◽  
Todd A. Miller ◽  
David C. Poole ◽  
Michael D. Delp
Keyword(s):  
Skeletal Muscle ◽  
Citrate Synthase ◽  
Fiber Type ◽  
Rank Order ◽  
Oxidative Capacity ◽  
Type I ◽  
Cross Sectional ◽  
Physiological Investigation ◽  
Combining Data ◽  
Type I Fibers

The hamster is a valuable biological model for physiological investigation. Despite the obvious importance of the integration of cardiorespiratory and muscular system function, little information is available regarding hamster muscle fiber type and oxidative capacity, both of which are key determinants of muscle function. The purpose of this investigation was to measure immunohistochemically the relative composition and size of muscle fibers composed of types I, IIA, IIX, and IIB fibers in hamster skeletal muscle. The oxidative capacity of each muscle was also assessed by measuring citrate synthase activity. Twenty-eight hindlimb, respiratory, and facial muscles or muscle parts from adult (144–147 g bw) male Syrian golden hamsters ( n=3) were dissected bilaterally, weighed, and frozen for immunohistochemical and biochemical analysis. Combining data from all 28 muscles analyzed, type I fibers made up 5% of the muscle mass, type IIA fibers 16%, type IIX fibers 39%, and type IIB fibers 40%. Mean fiber cross-sectional area across muscles was 1665 ± 328 μm2 for type I fibers, 1900 ± 417 μm2 for type IIA fibers, 3230 ± 784 μm2 for type IIX fibers, and 4171 ± 864 μm2 for type IIB fibers. Citrate synthase activity was most closely related to the population of type IIA fibers ( r=0.68, p<0.0001) and was in the rank order of type IIA > I > IIX > IIB. These data demonstrate that hamster skeletal muscle is predominantly composed of type IIB and IIX fibers.

Statistical Analysis of Fiber Area in Human Skeletal Muscle

2002 ◽  
Vol 27 (4) ◽  
pp. 415-422 ◽  
Author(s):  
Michael R.M. Mcguigan ◽  
William J. Kraemer ◽  
Michael R. Deschenes ◽  
Scott E. Gordon ◽  
Takashi Kitaura ◽  
...  
Keyword(s):  
Fiber Type ◽  
Cross Sectional Area ◽  
Type I ◽  
Fiber Types ◽  
Sectional Area ◽  
Cross Sectional ◽  
Fiber Area ◽  
Random Block ◽  
Type I Fibers ◽  
Accurate Reflection

Previous research has indicated that 50 fiber measurements per individual for type I and II fibers would be sufficient to characterize the fiber areas. This study replicated the work of McCall et al. (1998) using the three major fiber types (I, IIA, and IIB) and sampling larger populations of fibers. Random blocks of fibers were also examined to investigate how well they correlated with the overall mean average fiber area. Using random blocks of 50 fibers provided an accurate reflection of the type IIB fibers (r = 0.96-0.98) but not for the type I (r = 0.85-0.94) or IIA fibers (r = 0.80-0.91). Type I fibers were consistently reflected by a random block of 150 fibers (r = 0.95-0.98) while type IIA fibers required random blocks of 200 fibers (r = 0.94-0.98), which appeared to provide an accurate reflection of the cross-sectional area. These results indicate that for a needle biopsy different numbers of fibers are needed depending on the fiber type to accurately characterize the mean fiber population. Key words: fiber type, sample size, cross-sectional area, biopsy

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