CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - CONTRACTION KINETICS

1994 ◽  
Vol 187 (1) ◽  
pp. 275-293 ◽  
Author(s):  
D Stokes ◽  
R Josephson
Keyword(s):  
High Frequency ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Length Change ◽  
Shortening Velocity ◽  
Long Duration ◽  
Maximum Isometric Force ◽  
Small Muscle

1. The flagella (small appendages on the maxillipeds) of the crab Carcinus maenas beat regularly when active at about 10 Hz (15 °C). The beat of a flagellum is due to contraction of a single small muscle, the flagellum abductor (FA). The optimal stimulus frequency for tetanic contraction of the FA was about 200 Hz. When the muscle was stimulated at 10 Hz with paired stimuli per cycle, the interstimulus interval that maximized peak force was 2­4 ms, which corresponded well to the interspike intervals within bursts recorded from motor axons during normal beating. 2. Contraction of the isolated FA showed pronounced neuromuscular facilitation and many stimuli were needed to activate the muscle fully. The dependence on facilitation in isolated muscles appeared to be greater than that in vivo. It is suggested that neuromodulators in the blood of the crab enhance neuromuscular transmission and reduce the dependency on facilitation in intact animals. 3. The FA had a narrow length­tension curve. Tetanic tension became vanishingly small at muscle lengths less than about 90 % of the maximum in vivo length. The maximum length change of the muscle during in vivo contraction was about 5 %. 4. The maximum isometric force of the FA was low (about 6 N cm-2) but its shortening velocity was high. Vm, the maximum shortening velocity determined from isotonic shortening, was 4.0 muscle lengths s-1; V0, the maximum shortening velocity from slack test measurements, was about 8 lengths s-1. 5. The structure and physiology of the FA are compared with those of locust flight muscle, chosen because it too is a muscle capable of long-duration, high-frequency performance.

Work-dependent deactivation of a crustacean muscle

1999 ◽  
Vol 202 (18) ◽  
pp. 2551-2565 ◽  
Author(s):  
R.K. Josephson ◽  
D.R. Stokes
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Force Production ◽  
Muscle Length ◽  
Background Level ◽  
Shortening Velocity ◽  
Shortening Deactivation ◽  
Work Done

Active shortening of respiratory muscle L2B from the crab Carcinus maenas results in contractile deactivation, seen as (1) a decline of force during the course of isovelocity shortening, (2) a reduction in the rate of force redevelopment following shortening, (3) a depression of the level of isometric force reached following shortening, and (4) an accelerated relaxation at the end of stimulation. The degree of deactivation increases with increasing distance of shortening, decreases with increasing shortening velocity, and is approximately linearly related to the work done during shortening. Deactivation lasts many seconds if stimulation is maintained, but is largely although not completely removed if the stimulation is temporarily interrupted so that the force drops towards the resting level. Deactivation for a given distance and velocity of shortening increases with increasing muscle length above the optimum length for force production. Stimulating muscle L2B at suboptimal frequencies gives tetanic contractions that are fully fused but of less than maximal amplitude. The depression of force following shortening, relative to the force during an isometric contraction, is independent of the stimulus frequency used to activate the muscle, indicating that deactivation is not a function of the background level of stimulus-controlled muscle activation upon which it occurs. Deactivation reduces the work required to restretch a muscle after it has shortened, but it also lowers the force and therefore the work done during shortening. The net effect of deactivation on work output over a full shortening/lengthening cycle is unknown.

scholarly journals The Contractile Properties of a Crab Respiratory Muscle

1987 ◽  
Vol 131 (1) ◽  
pp. 265-287 ◽  
Author(s):  
ROBERT K. JOSEPHSON ◽  
DARRELL R. STOKES
Keyword(s):  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Muscle Length ◽  
Isometric Tension ◽  
Shortening Velocity ◽  
Force Velocity ◽  
Contraction And Relaxation ◽  
Full Activation ◽  
Stimulus Number

1. Contraction of scaphognathite muscle L2B of the green crab Carcinus maenas is strongly dependent on stimulus number and frequency. Single, supramaximal stimuli evoke little or no tension. When stimulated with shocks in either short bursts (10 stimuli in 0.5s or less) or long bursts (5 s of stimulation), the isometric tension from the muscle increases with increasing stimulus frequency to a maximum at about 150 Hz at 15°C, beyond which tension declines with further increase in stimulus frequency. 2. There can be facilitation of both contraction and relaxation between short bursts of stimuli. Facilitation of contraction is seen as increasing tension on successive bursts of a series, even when the interburst interval is long enough for relaxation to be completed during the interval. Interburst facilitation lasts at least 10 s. Facilitation of relaxation is seen as progressively faster relaxation from burst to burst of a series, and relaxation to lower tension levels when the interburst interval is so short that relaxation is incomplete in the interburst interval. 3. Maximum isometric tension occurs at muscle lengths slightly longer than the longest muscle length reached in vivo. Tension declines rapidly with changes in muscle length away from the optimum length. The maximum isometric tension was about 12 N cm−2. 4. The maximum shortening velocity of a tetanically activated muscle was determined as 1.9 lengthss−1 (Ls−1) by extrapolation of force-velocity curves to zero force and 3.3 Ls−1 by slack test measurements. 5. The scaphognathite muscle would be classified as a slow or tonic muscle on the basis of its requirements for multiple stimulation to reach full activation, and as a moderately fast muscle on the basis of its force-velocity properties.

scholarly journals Corticosteroid effects on isotonic contractile properties of rat diaphragm muscle

1997 ◽  
Vol 83 (4) ◽  
pp. 1062-1067 ◽  
Author(s):  
Roland H. H. Van Balkom ◽  
Wen-Zhi Zhan ◽  
Y. S. Prakash ◽  
P. N. Richard Dekhuijzen ◽  
Gary C. Sieck
Keyword(s):  
Isometric Force ◽  
Contractile Properties ◽  
Diaphragm Muscle ◽  
Peak Power Output ◽  
Rat Diaphragm ◽  
Fiber Morphology ◽  
Shortening Velocity ◽  
Maximum Isometric Force ◽  
Induced Changes ◽  
Isotonic Contractions

Van Balkom, Roland H. H., Wen-Zhi Zhan, Y. S. Prakash, P. N. Richard Dekhuijzen, and Gary C. Sieck. Corticosteroid effects on isotonic contractile properties of rat diaphragm muscle. J. Appl. Physiol. 83(4): 1062–1067, 1997.—The effects of corticosteroids (CS) on diaphragm muscle (Diam) fiber morphology and contractile properties were evaluated in three groups of rats: controls (Ctl), surgical sham and weight-matched controls (Sham), and CS-treated (6 mg ⋅ kg−1 ⋅ day−1prednisolone at 2.5 ml/h for 3 wk). In the CS-treated Diam, there was a selective atrophy of type IIx and IIb fibers, compared with a generalized atrophy of all fibers in the Sham group. Maximum isometric force was reduced by 20% in the CS group compared with both Ctl and Sham. Maximum shortening velocity in the CS Diamwas slowed by ∼20% compared with Ctl and Sham. Peak power output of the CS Diam was only 60% of Ctl and 70% of Sham. Endurance to repeated isotonic contractions improved in the CS-treated Diam compared with Ctl. We conclude that the atrophy of type IIx and IIb fibers in the Diam can only partially account for the CS-induced changes in isotonic contractile properties. Other factors such as reduced myofibrillar density or altered cross-bridge cycling kinetics are also likely to contribute to the effects of CS treatment.

Muscle function during jumping in frogs. I. Sarcomere length change, EMG pattern, and jumping performance

1996 ◽  
Vol 271 (2) ◽  
pp. C563-C570 ◽  
Author(s):  
G. J. Lutz ◽  
L. C. Rome
Keyword(s):  
Mechanical Properties ◽  
Muscle Function ◽  
Length Change ◽  
Operating Conditions ◽  
Mechanical Power ◽  
Shortening Velocity ◽  
Jumping Performance ◽  
Angular Velocities ◽  
High Level

We determined the influence of temperature on muscle function during jumping to better understand how the frog muscular system is designed to generate a high level of mechanical power. Maximal jumping performance and the in vivo operating conditions of the semimembranosus muscle (SM), a hip extensor, were measured and related to the mechanical properties of the isolated SM in the accompanying paper [Muscle function during jumping in frogs. II. Mechanical properties of muscle: implication for system design. Am. J. Physiol. 271 (Cell Physiol. 40): C571-C578, 1996]. Reducing temperature from 25 to 15 degrees C caused a 1.75-fold decline in peak mechanical power generation and a proportional decline in aerial jump distance. The hip and knee joint excursions were nearly the same at both temperatures. Accordingly, sarcomeres shortened over the same range (2.4 to 1.9 microns) at both temperatures, corresponding to myofilament overlap at least 90% of maximal. At the low temperature, however, movements were made more slowly. Angular velocities were 1.2- to 1.4-fold lower, and ground contact time was increased by 1.33-fold at 15 degrees C. Average shortening velocity of the SM was only 1.2-fold lower at 15 degrees C than at 25 degrees C. The low Q10 of velocity is in agreement with that predicted for muscles shortening against an inertial load.

CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - ACTIVATION PATTERNS IN VIVO

1994 ◽  
Vol 187 (1) ◽  
pp. 261-274
Author(s):  
R Josephson ◽  
D Stokes
Keyword(s):  
Coefficient Of Variation ◽  
High Frequency ◽  
Interspike Interval ◽  
Carcinus Maenas ◽  
Single Muscle ◽  
Stroke Frequency ◽  
Activation Patterns ◽  
Animal Mass ◽  
Animal Size

1. The flagella of crustaceans are small appendages, borne on the maxillipeds, which beat repetitively when active. Flagellar movement is brought about by contraction of a single muscle, the flagellum abductor (FA). 2. The stroke frequency of the flagella of the green crab, Carcinus maenas, was about 11 Hz at 15 °C and was relatively independent of animal size [frequency is proportional to (animal mass)-0.07], even though scaling considerations suggest that, for constant muscle stress, frequency should be proportional to mass-0.33. The coefficient of variation for intervals between successive strokes of a flagellum was about 4 %. 3. The FA is innervated by two excitatory motoneurones. Each of the neurones fired 0­5 times during a stroke. The interspike interval when a neurone fired more than once during a stroke was 3­4 ms.

In vivo supraspinatus muscle contractility and architecture in rabbit

2020 ◽  
Vol 129 (6) ◽  
pp. 1405-1412
Author(s):  
Sydnee A. Hyman ◽  
Mackenzie B. Norman ◽  
Shanelle N. Dorn ◽  
Shannon N. Bremner ◽  
Mary C. Esparza ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Isometric Force ◽  
Muscle Physiology ◽  
Mammalian Skeletal Muscle ◽  
Improved Method ◽  
Muscle Contractility ◽  
Supraspinatus Muscle ◽  
Contractile Stress ◽  
Maximum Isometric Force

We introduce an improved method to assess rabbit supraspinatus muscle physiology. Maximum isometric force measured for the rabbit supraspinatus was dramatically greater than previous reports in the literature. Consequently, the isometric contractile stress reported is almost 10 times greater than previous reports of rabbit supraspinatus, but similar to available literature of other mammalian skeletal muscle. We show that previous reports of peak supraspinatus isometric force were subphysiological by ∼90%

Effect of airway inflammation on smooth muscle shortening and contractility in guinea pig trachealis

1993 ◽  
Vol 265 (6) ◽  
pp. L549-L554 ◽  
Author(s):  
R. W. Mitchell ◽  
I. M. Ndukwu ◽  
K. Arbetter ◽  
J. Solway ◽  
A. R. Leff
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Neurogenic Inflammation ◽  
Isometric Force ◽  
Electrical Field Stimulation ◽  
Shortening Velocity ◽  
Lever System ◽  
Force Velocity

We studied the effect of either 1) immunogenic inflammation caused by aerosolized ovalbumin or 2) neurogenic inflammation caused by aerosolized capsaicin in vivo on guinea pig tracheal smooth muscle (TSM) contractility in vitro. Force-velocity relationships were determined for nine epithelium-intact TSM strips from ovalbumin-sensitized (OAS) vs. seven sham-sensitized controls and TSM strips for seven animals treated with capsaicin aerosol (Cap-Aer) vs. eight sham controls. Muscle strips were tethered to an electromagnetic lever system, which allowed isotonic shortening when load clamps [from 0 to maximal isometric force (Po)] were applied at specific times after onset of contraction. Contractions were elicited by supramaximal electrical field stimulation (60 Hz, 10-s duration, 18 V). Optimal length for each muscle was determined during equilibration. Maximal shortening velocity (Vmax) was increased in TSM from OAS (1.72 +/- 0.46 mm/s) compared with sham-sensitized animals (0.90 +/- 0.15 mm/s, P < 0.05); Vmax for TSM from Cap-Aer (0.88 +/- 0.11 mm/s) was not different from control TSM (1.13 +/- 0.08 mm/s, P = NS). Similarly, maximal shortening (delta max) was augmented in TSM from OAS (1.01 +/- 0.15 mm) compared with sham-sensitized animals (0.72 +/- 0.14 mm, P < 0.05); delta max for TSM from Cap-Aer animals (0.65 +/- 0.11 mm) was not different from saline aerosol controls (0.71 +/- 0.15 mm, P = NS). We demonstrate Vmax and delta max are augmented in TSM after ovalbumin sensitization; in contrast, neurogenic inflammation caused by capsaicin has no effect on isolated TSM contractility in vitro. These data suggest that airway hyperresponsiveness in vivo that occurs in association with immunogenic or neurogenic inflammation may result from different effects of these types of inflammation on airway smooth muscle.

Aminophylline increases submaximum power but not intrinsic velocity of shortening of frog muscle

1992 ◽  
Vol 73 (1) ◽  
pp. 71-74 ◽  
Author(s):  
B. M. Block ◽  
S. R. Barry ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscles ◽  
Isometric Force ◽  
Frog Muscle ◽  
Measured Parameter ◽  
Shortening Velocity ◽  
Force Development ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Maximum Isometric Force ◽  
Frequency Of Stimulation

We hypothesized that methylxanthines, such as aminophylline, increase the power developed by submaximally activated frog skeletal muscles by increasing the force developed at any given velocity of shortening. Frog semitendinosus muscles were excised and tested at 20 degrees C in oxygenated control and aminophylline Ringer solutions. Force-velocity relationships were determined and power was calculated from muscles stimulated at frequencies of 80 and 300 Hz. The 300-Hz frequency of stimulation produced a maximum rate of force development. In 50 and 500 microM aminophylline, twitch force increased by 25 +/- 12 and 75 +/- 13%, respectively. Aminophylline did not affect maximum isometric force generation or the shortening velocity at any relative load. At 80-Hz stimulation and in the presence of 500 microM aminophylline, power increased by an average of 11% at 10 of 14 relative loads. At maximum frequencies of stimulation, aminophylline had no effect on any measured parameter. We conclude that aminophylline increases the power developed by submaximally activated frog muscles through an increase in the force generated particularly at the lower velocities of shortening.

scholarly journals The maximum shortening velocity of muscle should be scaled with activation

1999 ◽  
Vol 86 (3) ◽  
pp. 1025-1031 ◽  
Author(s):  
John W. Chow ◽  
Warren G. Darling
Keyword(s):  
Isometric Force ◽  
Musculoskeletal Modeling ◽  
Type Model ◽  
Shortening Velocity ◽  
Activation Level ◽  
Maximum Activation ◽  
Force Velocity ◽  
Maximum Isometric Force ◽  
Release Method ◽  
Wrist Flexors

The purpose of this study was to determine whether the maximum shortening velocity ( V max) in Hill’s mechanical model (A. V. Hill. Proc. R. Soc. London Ser. B. 126: 136–195, 1938) should be scaled with activation, measured as a fraction of the maximum isometric force (Fmax). By using the quick-release method, force-velocity (F-V) relationships of the wrist flexors were gathered at five different activation levels (20–100% of maximum at intervals of 20%) from four subjects. The F-V data at different activation levels can be fitted remarkably well with Hill’s characteristic equation. In general, the shortening velocity decreases with activation. With the assumption of nonlinear relationships between Hill constants and activation level, a scaled V max model was developed. When the F-V curves for submaximal activation were forced to converge at the V max obtained with maximum activation (constant V max model), there were drastic changes in the shape of the curves. The differences in V max values generated by the scaled and constant V max models were statistically significant. These results suggest that, when a Hill-type model is used in musculoskeletal modeling, the V max should be scaled with activation.

Effect of physiological ADP concentrations on contraction of single skinned fibers from rabbit fast and slow muscles

1995 ◽  
Vol 268 (2) ◽  
pp. C480-C489 ◽  
Author(s):  
P. B. Chase ◽  
M. J. Kushmerick
Keyword(s):  
Isometric Force ◽  
Control Level ◽  
Diffusion Reaction ◽  
Fiber Types ◽  
Shortening Velocity ◽  
Slow Twitch ◽  
Fast Twitch ◽  
Apparent Equilibrium

To directly assess the possible role of ADP in muscle fatigue, we have studied the effect of physiological MgADP levels on maximum Ca(2+)-activated isometric force and unloaded shortening velocity (Vus) of single skinned fiber segments from rabbit fast-twitch (psoas) and slow-twitch (soleus) muscles. MgADP concentration was changed in a controlled and well-buffered manner by varying creatine (Cr) in solutions, which also contained MgATP, phosphocreatine (PCr), and creatine kinase (CK). To quantify ADP as a function of Cr added, we determined the apparent equilibrium constant (K') of CK for the conditions of our experiments (pH 7.1, 3 mM Mg2+, 12 degrees C): K' = (sigma [Cr]. sigma [ATP])/(sigma [PCr]. sigma [ADP]) = 260 +/- 3 (SE). In this manner, ADP was altered essentially as occurs during stimulation in vivo but without the concomitant changes in pH and P(i), which affect force and Vus. As ADP (and Cr) was increased, force and Vus decreased in both fiber types; at the highest ADP level used, 200 microM, normalized force was 96.6 +/- 1.7% for psoas (n = 6) and 93.7 +/- 2.8% for soleus (n = 6), and Vus was 80.4 +/- 2.4% for psoas and 91.3 +/- 7.7% for soleus. Diffusion-reaction calculations indicated that radial gradients of metabolite concentrations within fibers could not explain the small effects of ADP on fiber mechanics, and experiments verified that metabolite levels were well buffered within fibers by the CK reaction. Exogenous CK was added to bathing solutions at 290 U/ml, threefold above that necessary to maintain Vus independent of CK concentration; in the absence of PCr and exogenous CK, at least a fourfold increased MgATP was necessary to maintain Vus at the control level. Adenylate kinase activity was not detectable; thus myofibrillar adenosine-triphosphatase and exogenous CK activities were the major determinants of nucleotide levels within activated cells. Cr alone (in absence of PCr and exogenous CK) also decreased force and Vus, presumably by a nonspecific mechanism. Over the physiological range, altered ADP had little or no effect on force or Vus in well-buffered conditions. It is therefore likely that other factors decrease force and Vus during muscular fatigue.

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