The Phasic and Tonic Contraction in the Longitudinal Muscle of the Earthworm

1971 ◽  
Vol 55 (1) ◽  
pp. 111-122
Author(s):  
N. TASHIRO ◽  
T. YAMAMOTO
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Ions ◽  
Longitudinal Muscle ◽  
Divalent Cations ◽  
Muscle Length ◽  
Transition Metal Ions ◽  
Tonic Contraction ◽  
Active State ◽  
Muscle Fibres ◽  
Phasic Contraction

1. In extension of preceding studies on the mechanical properties of the longitudinal muscle fibres of the earthworm, the phasic and tonic contractions were analysed under various conditions. 2. The phasic contractions appeared on the tonic contraction which was maintained at a steady level by repetitive stimulation, and the tonic contraction decayed very slowly after cessation of stimulation. 3. The length-tension curve indicated that the phasic and tonic contractions were both affected similarly by changing the muscle length. 4. The mechanical ‘active state’ was investigated during the phasic and tonic contractions by means of the quick-release method. During the phasic contraction the ability to redevelop the tension was observed. During the early phase of the tonic contraction the muscle was in the ‘active state’, but the tonic contraction continued even after the tension redevelopment had nearly ceased. 5. The tonic contraction was absent when the temperature was raised to about 30 °C. 5-Hydroxytryptamine (2.5 x 10-6 M) decreased the tonic more than the phasic contraction. The tonic contraction disappeared completely in the presence of acetylcholine (5.5 x 10-4 M), while the phasic contraction was reduced but not abolished. γ-aminobutyric acid (10-6 to 5 x 10-4 M) had no effect on the contractions. 6. Transition-metal ions suppressed mainly the phasic contraction in the order of Mn2+ > Co2+ > Ni2+. The decrease in the phasic contraction was proportional to the logarithm of concentration of added divalent cations. The tonic contraction was also reduced but at higher concentration than the phasic contraction. 7. It is postulated that, by depolarization produced by electrical stimulation or by acetylcholine, calcium ions are released from the plasma membrane and also from the sarcoplasmic reticulum. The phasic contraction might be generated mainly by calcium ions released from the membrane, and the tonic contraction might be caused mainly by calcium ions released from the sarcoplasmic reticulum.

Mechanical Properties of the Longitudinal and Circular Muscle in the Earthworm

1971 ◽  
Vol 55 (1) ◽  
pp. 101-110
Author(s):  
N. TASHIRO
Keyword(s):  
Mechanical Properties ◽  
Longitudinal Muscle ◽  
Circular Muscle ◽  
Tonic Contraction ◽  
Muscle Fibres ◽  
Field Stimulation ◽  
Free Solution ◽  
Tension Development ◽  
Phasic Contraction

1. The mechanical properties of the longitudinal and circular muscles of the earthworm, Pheretima communissima, were studied in various solutions. 2. In the longitudinal muscle, field stimulation elicited two distinct waves of tension development, i.e. phasic and tonic contractions. But in the circular muscle, these components were not distinguishable. 3. The phasic contraction in the longitudinal muscle increased in sodium-free (tris) solution while the tonic contraction was abolished. Neither the phasic nor the tonic contraction, however, was influenced by tetrodotoxin (3 x 10-6 M), d-tubocurarine (1.4 x 10-5M), or atropine (3.5 x 10-5 M). 4. The contraction in the circular muscle was suppressed in sodium-free solution and also by tetrodotoxin (3 x 10-6 M), but was not affected by d-tubocurarine (1.4 x 10-5 M) or by atropine (3.5 x 10-5M). 5. It is speculated that the phasic contraction of the longitudinal muscle is triggered by a calcium spike, and the contraction in the circular muscle is preceded by a sodium spike in muscle fibres.

scholarly journals Tonic contraction and the control of relaxation in a chemically skinned molluscan smooth muscle.

1982 ◽  
Vol 79 (5) ◽  
pp. 821-834 ◽  
Author(s):  
F Cornelius
Keyword(s):  
Muscle Length ◽  
Tonic Contraction ◽  
Active State ◽  
Retractor Muscle ◽  
Muscle Preparation ◽  
Tension Development ◽  
Maximum Tension ◽  
Skinned Muscle ◽  
Catch State ◽  
Molluscan Smooth Muscle

The same functional states that characterize the living anterior byssus retractor muscle (ABRM) from Mytilus edulis can be initiated in the saponin-treated (chemically skinned) muscle preparation under controlled biochemical conditions. A tonic contraction was induced if the concentration of free Ca2+ was above approximately 10(7) M in the presence of Mg2+ and ATP. Maximum tension development was achieved at a Ca2+ concentration of approximately 10(4) M. Within these Ca2+ concentrations tension was always associated with the presence of 'active state," as indicated by a high recovery of tension after a quick release in muscle length. Tonic tension, and the associated active state was maintained for hours during these conditions irrespective of variations in both ionic strength and pH. Reduction of the Ca2+ concentration to below threshold for tension initiation during a tonic contraction immediately switched off the active state and relaxation of the muscle preparation resulted. However, the rate of relaxation was extremely low, leaving a substantial fraction of tension in the absence of active state. Both 5-hydroxytryptamine (5-HT) and cAMP accelerated this slow relaxation in the absence of Ca2+. Thus, this state was considered equivalent to the 'catch state" in the living ABRM. In the presence of Ca2+ concentrations above 10(7) M, cAMP did not affect either the maximum tension developed or the Ca2+ sensitivity of the chemically skinned muscle preparation.

Ca2+ and activation mechanisms in skeletal muscle

1991 ◽  
Vol 24 (1) ◽  
pp. 1-73 ◽  
Author(s):  
Christopher C. Ashley ◽  
Ian P. Mulligan ◽  
Trevor J. Lea
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Electrical Activity ◽  
Calcium Ions ◽  
Crucial Role ◽  
Striated Muscle ◽  
Surface Membrane ◽  
Muscle Fibres ◽  
Tubular System ◽  
Activation Mechanisms

It has been known for a number of years that calcium ions play a crucial role in excitation-contraction (e-c) coupling (Sandow, 1952). The majority of the calcium required for this process is derived, at least in vertebrate striated muscle fibres, from discrete intracellular stores located at sites within the cell: the terminal cysternae (tc)/junctional SR of the sarcoplasmic reticulum (SR) (Fig. 1 a). These storage sites not only form a compartment that is distinct from the sarcoplasm of the fibre, but they are also closely associated with the contractile elements, the myofibrils. The SR release sites are activated following the spread of electrical activity (Huxley and Taylor, 1958) along the transverse (T) tubular system (Eisenberg and Gage, 1967; Adrian et al. 1969a, b; Peachey, 1973) from the surface membrane (Bm).

scholarly journals Caffeine and micromolar Ca2+ concentrations can release Ca2+ from ryanodine-sensitive stores in crab and lobster striated muscle fibres

1996 ◽  
Vol 199 (11) ◽  
pp. 2419-2428 ◽  
Author(s):  
T Lea
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Striated Muscle ◽  
Abdominal Muscle ◽  
Isometric Tension ◽  
Muscle Fibres ◽  
Phasic Contraction ◽  
Crustacean Muscle ◽  
Time Integral ◽  
Variable Nature

Ca2+ release mechanisms were studied in striated muscle from the walking legs of crabs using isometric tension recordings from isolated myofibrillar bundles. Caffeine-induced phasic contractions had properties consistent with Ca2+ release from a sarcoplasmic store, which could be optimally loaded in the presence of ATP at pCa 6.4­6.1. Ryanodine (10 µmol l-1) abolished the caffeine-induced contractions and in solutions with low Ca2+ buffering (0.1 mmol l-1 EGTA) itself caused phasic contractions, indicative of Ca2+ release. Ca2+-induced Ca2+ release (CICR) was observed in a pCa 5.8 solution (buffered by 1 mmol l-1 EGTA) as a phasic contraction of variable nature, inhibited by ryanodine (10 µmol l-1), procaine (10 mmol l-1) or benzocaine (5 mmol l-1). Ca2+ release was measured as a function of releasing pCa by using the force­time integral of the caffeine-induced contraction as an estimate of the Ca2+ remaining in the store. After the Ca2+ store had been loaded for 2 min at pCa 6.6, CICR was measured in the presence of 1 mmol l-1 Mg2+, 1 mmol l-1 EGTA and 5 mmol l-1 ATP. The threshold pCa for CICR was 6.0­6.4 under these conditions and more than 90 % of stored Ca2+ was released in 1 min by pCa values in the range 3.5­5.3. Benzocaine totally inhibited the release and promoted extra Ca2+ loading. Preliminary experiments showed a similar caffeine-releasable store in lobster abdominal muscle, which was slightly less sensitive to free [Ca2+]. It is concluded that in crustacean muscle caffeine and micromolar [Ca2+] can release Ca2+ from a ryanodine-sensitive store, which in many respects is similar to the sarcoplasmic reticulum of vertebrate skeletal and cardiac muscle.

scholarly journals Polyelectrolyte Gels Formed by Filamentous Biopolymers: Dependence of Crosslinking Efficiency on the Chemical Softness of Divalent Cations

Gels ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 41
Author(s):  
Katrina Cruz ◽  
Yu-Hsiu Wang ◽  
Shaina A. Oake ◽  
Paul A. Janmey
Keyword(s):  
Alkaline Earth ◽  
Divalent Cations ◽  
Transition Metal Ions ◽  
Atomic Weight ◽  
Mechanical Resistance ◽  
Flexible Polymers ◽  
Interpenetrating Networks ◽  
Charge Densities ◽  
Polyelectrolyte Gels ◽  
Different Types

Filamentous anionic polyelectrolytes are common in biological materials. Some examples are the cytoskeletal filaments that assemble into networks and bundled structures to give the cell mechanical resistance and that act as surfaces on which enzymes and other molecules can dock. Some viruses, especially bacteriophages are also long thin polyelectrolytes, and their bending stiffness is similar to those of the intermediate filament class of cytoskeletal polymers. These relatively stiff, thin, and long polyelectrolytes have charge densities similar to those of more flexible polyelectrolytes such as DNA, hyaluronic acid, and polyacrylates, and they can form interpenetrating networks and viscoelastic gels at volume fractions far below those at which more flexible polymers form hydrogels. In this report, we examine how different types of divalent and multivalent counterions interact with two biochemically different but physically similar filamentous polyelectrolytes: Pf1 virus and vimentin intermediate filaments (VIF). Different divalent cations aggregate both polyelectrolytes similarly, but transition metal ions are more efficient than alkaline earth ions and their efficiency increases with increasing atomic weight. Comparison of these two different types of polyelectrolyte filaments enables identification of general effects of counterions with polyelectrolytes and can identify cases where the interaction of the counterions and the filaments exhibits stronger and more specific interactions than those of counterion condensation.

scholarly journals Evidence that coated vesicles isolated from brain are calcium-sequestering organelles resembling sarcoplasmic reticulum.

1977 ◽  
Vol 75 (1) ◽  
pp. 135-147 ◽  
Author(s):  
A L Blitz ◽  
R E Fine ◽  
P A Toselli
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Ions ◽  
Adenosine Triphosphatase ◽  
Sodium Dodecyl ◽  
Maximal Activity ◽  
Coated Vesicles ◽  
Potassium Oxalate ◽  
Triton X ◽  
Trapping Agent ◽  
The Brain

Coated vesicles from the brain have been purified to near morphological homogeneity by a modification of the method of Pearse. These vesicles resemble sarcoplasmic reticulum fragments isolated from skeletal muscle. They contain proteins with 100,000- and 55,000-dalton mol wt which co-migrate on polyacrylamide gels, in the presence of sodium dodecyl sulfate, with the two major proteins of the sarcoplasmic reticulum fragment. These vesicles contain adenosine triphosphatase (ATPase) activity which is stimulated by calcium ions in the presence of Triton X-100 (Rohm & Haas Co., Philadelphia, Pa.), displaying maximal activity at 8 x 10(-7) M Ca ++. They take up calcium ions from the medium, and this uptake is stimulated by ATP and by potassium oxalate, a calcium-trapping agent. The 100,000-dalton protein of the coated vesicles displays immunological reactivity with an antiserum directed against the 100,000-dalton, calcium-stimulated ATPase of the sarcoplasmic reticulum. As with the sarcoplasmic reticulum fragment, this protein becomes radiolabeled when coated vesicles are briefly incubated with gamma-labeled [32P]ATP. The possible functions of coated vesicles as calcium-sequestering organelles are discussed.

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