Contractile properties of hindlimb muscles in rat during surgical overload

1982 ◽  
Vol 242 (5) ◽  
pp. C259-C264 ◽  
Author(s):  
P. L. Freeman ◽  
A. R. Luff
Keyword(s):  
Dynamic Properties ◽  
Compensatory Hypertrophy ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Control Value ◽  
In Series ◽  
Isometric Twitch ◽  
Pentobarbital Sodium Anesthesia ◽  
Tetanic Tension

Structural and dynamic properties of the extensor digitorum longus (EDL) and soleus muscles of the rat under pentobarbital sodium anesthesia have been determined 4, 28, and 400 days after extirpation of the tibialis anterior and compared with the properties of muscles from the contralateral limb of the same animal. At 4 days the mass of the EDL increased by about 17%, but the maximum tetanic tension and tension per unit cross-sectional area decreased. The soleus showed a slight decrease in mass of about 6%. At 28 days the mass of the EDL had increased to 126% of the control value. Maximum isometric twitch and tetanic tensions increased, whereas tetanic tension per unit cross-sectional area returned to normal values; the number of sarcomeres in series increased, which led to an increase in the whole muscle speed of shortening. It is concluded that the synergistic EDL undergoes compensatory hypertrophy by the addition of contractile material in series and in parallel but without any change in the intrinsic properties of the muscle. The fibers of the antagonistic soleus shorten slightly but are otherwise unchanged.

Tenotomy and repair of latissimus dorsi muscles in rats: implications for transposed muscle grafts

1993 ◽  
Vol 75 (3) ◽  
pp. 1294-1299 ◽  
Author(s):  
V. A. Kadhiresan ◽  
P. J. Guelinckx ◽  
J. A. Faulkner
Keyword(s):  
Muscle Mass ◽  
Latissimus Dorsi ◽  
Cross Sectional Area ◽  
Specific Force ◽  
Sectional Area ◽  
Average Force ◽  
Cross Sectional ◽  
Absolute Power ◽  
Control Value ◽  
Optimum Velocity

The functional properties of latissimus dorsi (LTD) muscles were evaluated 160 to 180 days after tenotomy and repair, when grafts had stabilized. Our hypothesis was that, compared with control LTD muscles, LTD grafts would develop less absolute force and power but that the specific force and normalized power would not differ. Expressed as a percentage of the value for control LTD muscles, values for grafts were 67% for muscle mass, 74% for mean single fiber cross-sectional area, 56% for maximum absolute isometric tetanic force, 64% for maximum absolute average force during shortening, and 70% for maximum absolute power. Compared with control LTD muscles, grafts showed no significant differences either in the number of fibers in the total muscle cross section or in the optimum velocity for the development of power. When force and power of grafts were normalized for total fiber cross-sectional area and mass, respectively, only the value for maximum specific force (84% of control value) was significant. The mechanisms responsible for the decrease in specific force after tenotomy and repair are not known. In contrast to the deficit in maximum specific force, the 30% deficit in maximum absolute power of grafts compared with control LTD muscles was explained completely by the 33% smaller muscle mass.

Morphological observations of motor units connected in-series to Golgi tendon organs

1986 ◽  
Vol 55 (1) ◽  
pp. 147-162 ◽  
Author(s):  
J. M. Spielmann ◽  
E. K. Stauffer
Keyword(s):  
Discharge Rate ◽  
Muscle Fibers ◽  
Motor Units ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Golgi Tendon Organs ◽  
In Series ◽  
The Cross ◽  
Tendon Organs

The glycogen-depletion technique (17, 32) has been used to examine the functional and morphological relationships between single isolated motor units (MUs) and single isolated Golgi tendon organs (GTOs) that were excited by the MUs in the soleus muscle of the cat. All MUs whose twitch contraction generated a brisk discharge from the GTOs during the rising and plateau phase of force development had a muscle fiber attached specifically to the proximal end of the GTOs. A significant (P less than 0.05) linear relationship was found between GTO discharge rate and the cross-sectional area of the muscle fibers that connected to a receptor. This was true when the correlation was calculated between firing rate and 1) the cross-sectional area of the entire collection of muscle fibers that connected in series to the GTOs; and 2) for the cross-sectional areas of the individually depleted muscle fibers that inserted on the GTO sample. These findings support the notion that the most physiologically relevant input for GTOs arises from the MUs that are attached directly in-series with the receptor.

Effect of hindlimb unloading on rat soleus fiber force, stiffness, and calcium sensitivity

1995 ◽  
Vol 79 (5) ◽  
pp. 1796-1802 ◽  
Author(s):  
K. S. McDonald ◽  
R. H. Fitts
Keyword(s):  
Time Course ◽  
Fiber Diameter ◽  
Isometric Force ◽  
Calcium Sensitivity ◽  
Cross Sectional Area ◽  
Hindlimb Unloading ◽  
Sectional Area ◽  
Cross Sectional ◽  
Control Value ◽  
Cross Bridges

The purpose of this study was to examine the time course of change in soleus muscle fiber peak force (N), tension (Po, kN/m2), elastic modulus (Eo), and force-pCa and stiffness-pCa relationships. After 1, 2, or 3 wk of hindlimb unloading (HU), single fibers were isolated and placed between a motor arm and a transducer, and fiber diameter, peak absolute force, Po, Eo, and force-pCa and stiffness-pCa relationships were characterized. One week of HU resulted in a significant reduction in fiber diameter (68 +/- 2 vs 57 +/- 1 microns), force (3.59 +/- 0.15 vs. 2.19 +/- 0.12 x 10(-4) N), Po (102 +/- 4 vs. 85 +/- 2 kN/m2), and Eo (1.96 +/- 0.12 vs. 1.37 +/- 0.13 x 10(7) N/m2), and 2 wk of HU caused a further decline in fiber diameter (45 +/- 1 microns), force (1.31 +/- 0.06 x 10(-4) N), and Eo (0.96 +/- 0.09 x 10(7) N/m2). Although the mean fiber diameter and absolute force continued to decline through 3 wk of HU, Po recovered to values not significantly different from control. The Po/Eo ratio was significantly increased after 1 (5.5 +/- 0.3 to 7.1 +/- 0.6), 2, and 3 wk of HU, and the 2-wk (9.5 +/- 0.4) and 3-wk (9.4 +/- 0.8) values were significantly greater than the 1-wk values. The force-pCa and stiffness-pCa curves were shifted rightward after 1, 2, and 3 wk of HU. At 1 wk of HU, the Ca2+ sensitivity of isometric force, assessed by Ca2+ concentration required for half-maximal force, was increased from the control value of 1.83 +/- 0.12 to 2.30 +/- 0.10 microM. In conclusion, after HU, the decrease in soleus fiber Po can be explained by a reduction in the number of myofibrillar cross bridges per cross-sectional area. Our working hypothesis is that the loss of contractile protein reduces the number of cross bridges per cross-sectional area and increases the filament lattice spacing. The increased spacing reduces cross-bridge force and stiffness, but Po/Eo increases because of a quantitatively greater effect on stiffness.

Mechanical deficit persists during long-term muscle hypertrophy

1990 ◽  
Vol 69 (3) ◽  
pp. 861-867 ◽  
Author(s):  
S. C. Kandarian ◽  
T. P. White
Keyword(s):  
Isometric Force ◽  
Force Production ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Plantaris Muscle ◽  
Cross Sectional ◽  
Control Value ◽  
Muscle Cross Sectional Area ◽  
Synergistic Muscle

Hypotheses were tested that the deficit in maximum isometric force normalized to muscle cross-sectional area (i.e., specific Po, N/cm2) of hypertrophied muscle would return to control value with time and that the rate and magnitude of adaptation of specific force would not differ between soleus and plantaris muscles. Ablation operations of the gastrocnemius and plantaris muscles or the gastrocnemius and soleus muscles were done to induce hypertrophy of synergistic muscle left intact in female Wistar rats (n = 47) at 5 wk of age. The hypertrophied soleus and plantaris muscles and control muscles from other age-matched rats (n = 22) were studied from days 30 to 240 thereafter. Po was measured in vitro at 25 degrees C in oxygenated Krebs-Ringer bicarbonate. Compared with control values, soleus muscle cross-sectional area increased 41-15% from days 30 to 240 after ablation, whereas Po increased 11 and 15% only at days 60 and 90. Compared with control values, plantaris muscle cross-sectional area increased 52% at day 30, 40% from days 60 through 120, and 15% at day 240. Plantaris muscle Po increased 25% from days 30 to 120 but at day 240 was not different from control value. Changes in muscle architecture were negligible after ablation in both muscles. Specific Po was depressed from 11 to 28% for both muscles at all times. At no time after the ablation of synergistic muscle did the increased muscle cross-sectional area contribute fully to isometric force production.

The role of ascorbic acid and exercise in chronic ischemia of skeletal muscle in rats

2007 ◽  
Vol 102 (1) ◽  
pp. 321-330 ◽  
Author(s):  
T. Loizidis ◽  
A. Sioga ◽  
L. Economou ◽  
A. Frosinis ◽  
A. Kyparos ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Vitamin C ◽  
Structural Damage ◽  
Cross Sectional Area ◽  
Muscle Performance ◽  
Sectional Area ◽  
Cross Sectional ◽  
Edl Muscle ◽  
Tetanic Tension ◽  
Vit C

This study was designed to investigate the effects of peripheral arterial insufficiency, exercise, and vitamin C administration on muscle performance, cross-sectional area, and ultrastructural morphology in extensor digitorum longus (EDL) and soleus (Sol) muscles in rats. Adult Wistar rats were assigned to ischemia alone (isch), ischemia-exercised (exe), ischemia-vitamin C (vit C), and ischemia-exercise-vitamin C (vit C + exe) groups. Ischemia was achieved via unilateral ligation of the right common iliac artery. Contralateral muscles within the same animal served as controls. Exercise protocol consisted of 50-min intermittent level running performed every other day for 5 days. Vitamin C (100 mg/kg body wt) was administered intraperitoneally on a daily basis throughout the 14 days of the experiment. With regard to the EDL muscle, ischemia alone reduced muscle strength, which was not recovered after vitamin C administration. Exercise alone following ischemia induced the most severe structural damage and cross-sectional area decrease in the muscle, yet the reduction in tetanic tension was not significant. Exercise in conjunction with vitamin C administration preserved ischemia-induced EDL muscle tetanic tension. In the Sol muscle, a significant reduction in single twitch tension after vitamin C administration was found, whereas the tetanic force of the ischemic Sol was not significantly decreased compared with the contralateral muscles in any group. Ischemic Sol muscle cross-sectional area was reduced in all but the exe groups. In Sol, muscle strength was reduced in the vit C group, and mean cross-sectional area of ischemic Sol muscles was reduced in all groups except the exe group. These results illustrate that mild exercise, combined with a low dose of vitamin C supplementation, may have beneficial effects on ischemic EDL muscle with a smaller effect on the Sol muscle.

scholarly journals The generation of non-linear solute gradients for chromatography by using only simple apparatus

1981 ◽  
Vol 193 (3) ◽  
pp. 991-996 ◽  
Author(s):  
F Solano-Muñoz ◽  
W G Bardsley
Keyword(s):  
General Theory ◽  
Single Channel ◽  
Cross Sectional Area ◽  
Theoretical Treatment ◽  
Peristaltic Pump ◽  
Sectional Area ◽  
Cross Sectional ◽  
Simple Apparatus ◽  
Time Profiles ◽  
In Series

It is shown that by using only a series of tubes with constant cross-sectional area and a single-channel peristaltic pump, it is possible to produce solute gradients with time profiles that are concave, convex, sigmoid or even with turning points. The general theory for predicting gradients, by using tubes in series that are either open or closed to the atmosphere, is presented, and the equations using three compartments are given. Experiments are described that support the usefulness and accuracy of such a theoretical treatment.

Viscoelastic properties of the contracting detrusor. II. Experimental approach

1991 ◽  
Vol 261 (2) ◽  
pp. C364-C375 ◽  
Author(s):  
J. G. Venegas ◽  
J. P. Woll ◽  
S. B. Woolfson ◽  
E. G. Cravalho ◽  
N. Resnick ◽  
...  
Keyword(s):  
Muscle Length ◽  
Companion Paper ◽  
Cross Sectional Area ◽  
Detrusor Muscle ◽  
Sectional Area ◽  
Positive Dependence ◽  
Muscle Properties ◽  
Cross Sectional ◽  
In Series ◽  
Viscous Element

Mechanical properties of detrusor muscle were studied with small-amplitude oscillatory volume perturbations in isometrically contracting bladders of anesthetized dogs. Contractions were studied at oscillatory frequencies (f) of 2 and 4 Hz and at bladder volumes (Vbl) ranging from 30 to 110 ml. The magnitude of bladder hydrodynamic stiffness (magnitude of G) increased linearly with mean detrusor pressure (Pdet) while the phase angle remained relatively constant during contraction. The slope (mG) of magnitude of G-Pdet relations had a positive dependence on f and a negative dependence on Vbl. Analysis of oscillatory data, described in the companion paper, was performed using incremental lumped-parameter models consisting of a spring with incremental constant (S = dF/dL), a viscous element with incremental viscosity (b = dF/du), and a mass (m). Only the model where elastic and viscous elements were placed in series with each other and in parallel with mass was compatible with the experimental data. Both S and b increased linearly with effective force (F), defined as Pdet times the cross-sectional area of the intravesical cavity. Slopes of the S-F and b-F relationships (ms and mb) were independent of Vbl and varied only slightly with f. The importance of this finding stems from recognizing that ms and mb correspond to the exponential coefficients of nonlinear series elastic and internal viscosity elements. These parameters, when normalized by resting muscle length, represent fundamental muscle properties independent of muscle cross-sectional area, stretch, or level of activation and compare well with parameters derived from other muscle systems using techniques such as quick releases and isotonic contractions.

Cold inhibition of cell volume regulation during the freezing of insect malpighian tubules.

1998 ◽  
Vol 201 (14) ◽  
pp. 2195-2204 ◽  
Author(s):  
D S Neufeld ◽  
J P Leader
Keyword(s):  
Low Temperature ◽  
Cell Volume ◽  
Volume Regulation ◽  
Cross Sectional Area ◽  
Malpighian Tubules ◽  
Sectional Area ◽  
Cross Sectional ◽  
Hyperosmotic Shock ◽  
Control Value ◽  
The Cross

Cells in freeze-tolerant tissues must survive substantial shrinkage during exposure to the hyperosmolarity that results as solutes are excluded from extracellular ice. We investigated the possibility that this hyperosmotic shock elicits an acute regulatory volume increase (RVI) by monitoring the response of epithelial cell volume in the Malpighian tubules of the New Zealand alpine weta (Hemideina maori) during exposure to low temperature/hyperosmolarity (mimicking freezing conditions) or during an actual freeze/thaw cycle. The cross-sectional area of cells in isolated Malpighian tubules was measured using differential interference contrast microscopy. At 20 degrees C, cells held in saline containing 400 mmol1-1 glucose exhibit an RVI in response to hyperosmotic shock. Cross-sectional area decreased by 30% immediately after a change from iso-osmotic (0.7 osmol1-1) to hyper-osmotic saline (2.1 osmol1-1, equal to the osmotic shock encountered during freezing to -4 degrees C) and then returned to 21% below the control value 30 min after the exposure. Although substantial cellular function of Malpighian tubules was retained at low temperature (the rate of fluid secretion by isolated tubules at 4 degrees C was 72% of that measured at 20 degrees C), no RVI was observed at 0% degrees C; cross-sectional area was 39% below the control value immediately after the hyperosmotic exposure and 36% below the control value 30 min after hyperosmotic exposure. Dibutyryl cyclic AMP potentiated the RVI observed at 20 degrees C, but failed to elicit an RVI at 0 degrees C. A substantial RVI was also absent when the saline contained trehalose rather than glucose, regardless of whether the tubules were held at 20 degrees C or 0 degrees C. The cross-sectional area of cells in saline containing glucose remained at approximately 30% below the control value during an entire 30 min period of actual freezing to -4 degrees C, suggesting that an acute volume regulatory response was in fact inhibited during mild freezing. The inhibition of an acute RVI during mild freezing may serve to avoid the energetic expenditure associated with volume regulation at a time when the normal defence of cell volume appears to be unnecessary.

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