Sarcomere length control in striated muscle

1982 ◽  
Vol 242 (3) ◽  
pp. H411-H420 ◽  
Author(s):  
R. van Heuningen ◽  
W. H. Rijnsburger ◽  
H. E. ter Keurs
Keyword(s):  
Sarcomere Length ◽  
Striated Muscle ◽  
Feedforward Control ◽  
Muscle Length ◽  
Transient Behavior ◽  
Loop Filter ◽  
Internal Position ◽  
Optimal Damping ◽  
Internal Velocity ◽  
Muscle Responses

A system that makes control of muscle length (ML), sarcomere length (SL), and force (F) possible in striated muscle preparations is described. SL was measured by light diffraction techniques and two diffractometers. Control was performed by influencing ML with a penmotor system with a frequency response of 190 Hz. SL or F could be controlled by interrupting the internal position (i.e., ML) feedback of the motor and by closing the respective loop. Velocity feedback of the motor through an internal velocity coil was maintained in all cases for optimal damping. Steady-state error of the system was minimized by an integrating loop filter. The feedback path was selected by means of potentiometers or analog switches. Electronic stops in the circuit protected the muscle against excessive stretch and load. A microprocessor-based average-response computer could be used for feedforward control to eliminate noise or to analyze longitudinal uniformity of the muscle. Responses of rat cardiac trabeculae during SL and F control are shown. Transient behavior of SL and F during control and measures to eliminate the transients are discussed.

Morphological Basis of the Disparity Between Muscle Length and Sarcomere Length in the Myocardium

1973 ◽  
Vol 31 ◽  
pp. 422-423
Author(s):  
G.E. Adomian ◽  
L. Chuck ◽  
W.W. Pannley
Keyword(s):  
Cardiac Muscle ◽  
Sarcomere Length ◽  
Muscle Length ◽  
Contractile Force ◽  
Direct Function ◽  
Morphological Basis ◽  
Tension Curve

Sonnenblick, et al, have shown that sarcomeres change length as a function of cardiac muscle length along the ascending portion of the length-tension curve. This allows the contractile force to be expressed as a direct function of sarcomere length. Below L max, muscle length is directly related to sarcomere length at lengths greater than 85% of optimum. However, beyond the apex of the tension-length curve, i.e. L max, a disparity occurs between cardiac muscle length and sarcomere length. To account for this disproportionate increase in muscle length as sarcomere length remains relatively stable, the concept of fiber slippage was suggested as a plausible explanation. These observations have subsequently been extended to the intact ventricle.

scholarly journals Stretch and quick release of rat cardiac trabeculae accelerates Ca2+ waves and triggered propagated contractions

2001 ◽  
Vol 281 (5) ◽  
pp. H2133-H2142 ◽  
Author(s):  
Yuji Wakayama ◽  
Masahito Miura ◽  
Yoshinao Sugai ◽  
Yutaka Kagaya ◽  
Jun Watanabe ◽  
...  
Keyword(s):  
Strain Gauge ◽  
Sarcomere Length ◽  
Muscle Length ◽  
Laser Diffraction ◽  
Active Force ◽  
Quick Release ◽  
Rat Hearts ◽  
Initiation And Propagation ◽  
Intracellular Ca ◽  
Ventricular Trabeculae

Rapid shortening of active cardiac muscle [quick release (QR)] dissociates Ca2+ from myofilaments. We studied, using muscle stretches and QR, whether Ca2+ dissociation affects triggered propagated contractions (TPCs) and Ca2+waves. The intracellular Ca2+ concentration was measured by a SIT camera in right ventricular trabeculae dissected from rat hearts loaded with fura 2 salt, force was measured by a silicon strain gauge, and sarcomere length was measured by laser diffraction while a servomotor controlled muscle length. TPCs ( n = 27) were induced at 28°C by stimulus trains (7.5 s at 2.65 ± 0.13 Hz) at an extracellular Ca2+ concentration ([Ca2+]o) = 2.0 mM or with 10 μM Gd3+ at [Ca2+]o = 5.2 ± 0.73 mM. QR during twitch relaxation after a 10% stretch for 100–200 ms reduced both the time between the last stimulus and the peak TPC (PeakTPC) and the time between the last stimulus and peak Ca2+ wave (PeakCW) and increased PeakTPC and PeakCW ( n= 13) as well as the propagation velocity ( V prop; n = 8). Active force during stretch also increased V prop( r = 0.84, n = 12, P < 0.01), but Gd3+ had no effect ( n = 5). These results suggest that Ca2+ dissociation by QR during relaxation accelerates the initiation and propagation of Ca2+ waves.

Relation of sarcomere length and muscle length in resting myocardium

1970 ◽  
Vol 218 (5) ◽  
pp. 1412-1416 ◽  
Author(s):  
AF Grimm ◽  
KV Katele ◽  
R Kubota ◽  
WV Whitehorn
Keyword(s):  
Sarcomere Length ◽  
Muscle Length

Active state plateau and latency in mammalian striated muscle

1961 ◽  
Vol 200 (4) ◽  
pp. 667-671 ◽  
Author(s):  
Forbes H. Norris
Keyword(s):  
Latent Period ◽  
Striated Muscle ◽  
Muscle Length ◽  
Single Stimulus ◽  
Active State ◽  
Tension Development ◽  
Maximum Tension ◽  
Tension Curves ◽  
Tetanic Tension

The active state plateau in rat striated muscle was studied by superimposition of tension curves resulting from one and two stimuli. The plateau ends 4.0 ± 0.1 msec. after stimulation in rat striated muscle at 36°C. The time to the end of the plateau is 3.4 ± 0.1 times the latent period. During the plateau, response to a second stimulus appears after increased mechanical latency. The second stimulus can also result in tension development at rates nearly twice those reached after a single stimulus. This effect has a peak which about corresponds to the end of the active state plateau, but precedes the peak of the curve for maximum tension. Correct timing of the second stimulus can result in about 60% of tetanic tension. The use of thiopental, gallamine, tubocurarine and changes in muscle length did not affect these results.

scholarly journals THE RELATIONSHIP BETWEEN MYOFILAMENT PACKING DENSITY AND SARCOMERE LENGTH IN FROG STRIATED MUSCLE

1967 ◽  
Vol 33 (2) ◽  
pp. 255-263 ◽  
Author(s):  
Philip W. Brandt ◽  
Enrique Lopez ◽  
John P. Reuben ◽  
Harry Grundfest
Keyword(s):  
Cross Sections ◽  
Packing Density ◽  
Sarcomere Length ◽  
Striated Muscle ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
Semitendinosus Muscle ◽  
Direct Function ◽  
Microscopic Studies

In cross-sections of single fibers from the frog semitendinosus muscle the number of thick myofilaments per unit area (packing density) is a direct function of the sarcomere length. Our data, derived from electron microscopic studies, fit well with other data derived from in vivo, low-angle X-ray diffraction studies of whole semitendinosus muscles. The data are consistent with the assumption that the sarcomere of a fibril maintains a constant volume during changes in sarcomere length. The myofilament lattice, therefore, expands as the sarcomere shortens. Since the distance between adjacent myofilaments is an inverse square root function of sarcomere length, the interaction of the thick and the thin myofilaments during sarcomere shortening may occur over distances which increase 70 A or more. The "expanding-sarcomere, sliding-filament" model of sarcomere shortening is discussed in terms of the current concepts of muscle architecture and contraction.

scholarly journals POLARIZED LIGHT OBSERVATIONS ON STRIATED MUSCLE CONTRACTION IN A MITE

1967 ◽  
Vol 32 (1) ◽  
pp. 169-179 ◽  
Author(s):  
John F. Aronson
Keyword(s):  
Light Microscopy ◽  
Sarcomere Length ◽  
Striated Muscle ◽  
Polarized Light ◽  
Rate Of Change ◽  
Filament Length ◽  
Relative Movement ◽  
Significant Difference ◽  
Average Slope ◽  
Region Length

Contraction of individual sarcomeres within the living mite Tarsonemus sp. was observed by polarized light microscopy. In unflattened animals the usual range of contraction was such that the minimum sarcomere length approximated the length of the A region, and the maximum sarcomere length was about twice the length of the A region. The central sarcomeres of the dorsal metapodosomal muscles were observed in detail. The A band length increased slightly with increasing sarcomere length since the regression of I region length on sarcomere length had an average slope of 0.91. When the A band length in a sarcomere which was shortening was compared with the length when the same sarcomere lengthened, no significant difference was seen. The A band of each sarcomere seemed to act as a not too rigid limit to further shortening; this agreed with the reversible shortening of a muscle in which the A band had been experimentally shortened. An H region was visible at long sarcomere lengths and was not visible at short sarcomere lengths, even when the muscle was actively shortening. The rate of change of H region length with sarcomere length suggested that I filament length may increase as sarcomere length increases. Despite this effect and the small increase in A length with sarcomere length, the results are considered to be consistent with a model in which shortening occurs by the relative movement of A and I filaments, with little or no change in length of either set of filaments. Sarcomere shortening was clearly associated with an increase in the retardation of the A region.

Musculoskeletal parameters of muscles crossing the shoulder and elbow and the effect of sarcomere length sample size on estimation of optimal muscle length

2004 ◽  
Vol 19 (7) ◽  
pp. 664-670 ◽  
Author(s):  
Joseph Langenderfer ◽  
Seth A Jerabek ◽  
Vijay B Thangamani ◽  
John E Kuhn ◽  
Richard E Hughes
Keyword(s):  
Sample Size ◽  
Sarcomere Length ◽  
Muscle Length

Models of contractile units and their assembly in smooth muscle

2005 ◽  
Vol 83 (10) ◽  
pp. 825-831 ◽  
Author(s):  
Farah Ali ◽  
Peter D Paré ◽  
Chun Y Seow
Keyword(s):  
Smooth Muscle ◽  
Striated Muscle ◽  
Dense Body ◽  
Unit Length ◽  
Muscle Length ◽  
Thick Filament ◽  
Contractile Apparatus ◽  
Thin Filaments ◽  
Dense Bodies ◽  
In Series

It is believed that the contractile filaments in smooth muscle are organized into arrays of contractile units (similar to the sarcomeric structure in striated muscle), and that such an organization is crucial for transforming the mechanical activities of actomyosin interaction into cell shortening and force generation. Details of the filament organization, however, are still poorly understood. Several models of contractile filament architecture are discussed here. To account for the linear relationship observed between the force generated by a smooth muscle and the muscle length at the plateau of an isotonic contraction, a model of contractile unit is proposed. The model consists of 2 dense bodies with actin (thin) filaments attached, and a myosin (thick) filament lying between the parallel thin filaments. In addition, the thick filament is assumed to span the whole contractile unit length, from dense body to dense body, so that when the contractile unit shortens, the amount of overlap between the thick and thin filaments (i.e., the distance between the dense bodies) decreases in exact proportion to the amount of shortening. Assembly of the contractile units into functional contractile apparatus is assumed to involve a group of cells that form a mechanical syncytium. The contractile apparatus is assumed malleable in that the number of contractile units in series and in parallel can be altered to accommodate strains on the muscle and to maintain the muscle's optimal mechanical function.Key words: contraction model, ultrastructure, length adaptation, plasticity.

scholarly journals Polarization of Tryptophan Fluorescence from Single Striated Muscle Fibers

1972 ◽  
Vol 59 (1) ◽  
pp. 103-120 ◽  
Author(s):  
C. G. dos Remedios ◽  
R. G. C. Millikan ◽  
M. F. Morales
Keyword(s):  
Sarcomere Length ◽  
Striated Muscle ◽  
Muscle Fibers ◽  
Tryptophan Fluorescence ◽  
Thin Filaments ◽  
A Value ◽  
Striated Muscle Fibers ◽  
Types Of Muscle Fibers ◽  
Cross Bridges ◽  
Contraction And Relaxation

Instrumentation has been developed to detect rapidly the polarization of tryptophan fluorescence from single muscle fibers in rigor, relaxation, and contraction. The polarization parameter (P⊥) obtained by exiciting the muscle tryptophans with light polarized perpendicular to the long axis of the muscle fiber had a magnitude P⊥ (relaxation) &gt; P⊥ (contraction) &gt; P⊥ (rigor) for the three types of muscle fibers examined (glycerinated rabbit psoas, glycerinated dorsal longitudinal flight muscle of Lethocerus americanus, and live semitendinosus of Rana pipiens). P⊥ from single psoas fibers in rigor was found to increase as the sarcomere length increased but in relaxed fibers P⊥ was independent of sarcomere length. After rigor, pyrophosphate produced little or no change in P⊥, but following an adenosine triphosphate (ATP)-containing solution, pyrophosphate produced a value of P⊥ that fell between the contraction and relaxation values. Sinusoidal or square wave oscillations of the muscle of amplitude 0.5–2.0% of the sarcomere length and frequency 1, 2, or 5 Hz were applied in rigor when the myosin cross-bridges are considered to be firmly attached to the thin filaments. No significant changes in P⊥ were observed in either rigor or relaxation. The preceding results together with our present knowledge of tryptophan distribution in the contractile proteins has led us to the conclusion that the parameter P⊥ is a probe of the contractile state of myosin which is probably sensitive to the orientation of the myosin S1 subfragment.

scholarly journals Forelimb unloading impairs glenohumeral muscle development in growing rats

2020 ◽  
Author(s):  
Sophia K. Tushak ◽  
Margaret K. Tamburro ◽  
Emily B. Fawcett ◽  
Lauren E. Merritt LE ◽  
Katherine R. Saul ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Muscle Development ◽  
Sarcomere Length ◽  
Glenohumeral Joint ◽  
Neuromuscular Disorders ◽  
Muscle Length ◽  
Hindlimb Unloading ◽  
Growing Rats ◽  
Musculoskeletal Development ◽  
Long Head

AbstractProper joint loading is essential for healthy musculoskeletal development. Many pediatric neuromuscular disorders cause irreversible muscle impairments resulting from both physiological changes and mechanical unloading of the joint. While previous studies have examined the effects of hindlimb unloading on musculoskeletal development in the lower limb, none have examined solely forelimb unloading. Thus, a large deficit in knowledge of the effect of upper limb unloading exists and must be addressed in order to better understand how the glenohumeral joint adapts during development. Two forelimb unloading models were developed to study the effects of varying degrees of unloading on the glenohumeral joint in growing rats: forelimb suspension (n=6, intervention 21 days post-natal) with complete unloading of both limbs via a novel suspension system and forearm amputation (n=8, intervention 3-6 days post-natal) with decreased loading and limb use in one limb after below-elbow amputation. After 8 weeks of unloading, changes in muscle architecture and composition were examined in ten muscles surrounding the shoulder. Results were compared to control rats from a previous study (n=8). Both methods of altered loading significantly affected muscle mass, sarcomere length, and optimal muscle length compared to control rats, with the biceps long head and triceps long head observing the most marked differences. Forearm amputation also significantly affected muscle mass, sarcomere length, and optimal muscle length in the affected limb relative to the contralateral limb. Muscle composition, assessed by collagen content, remained unchanged in all groups. This study demonstrated that forearm amputation, which was administered closer to birth, had greater effects on muscle than forelimb suspension, which was administered a few weeks later than amputation.

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