scholarly journals Calcium-Activated Tension of Skinned Muscle Fibers of the Frog

1974 ◽  
Vol 63 (6) ◽  
pp. 722-739 ◽  
Author(s):  
Robert E. Godt
Keyword(s):  
Thin Filament ◽  
Muscle Fibers ◽  
Creatine Phosphate ◽  
Isometric Tension ◽  
Skinned Fibers ◽  
University Of Wisconsin ◽  
Skinned Muscle ◽  
Physiology And Biochemistry ◽  
Calcium Affinity ◽  
Similar Solutions

The influence of MgATP on the Ga++-activated isometric tension of skinned frog muscle fibers was examined in solutions containing: Mg++ = 5 mM, creatine phosphate (CP) = 14.5 mM, creatinephosphokinase (CPK) = 1 mg/ml, total EGTA = 7 mM, CaCl2, KCl, imidazole ≥ 20 mM so that ionic strength = 0.15, pH = 7.00, and MgATP = 2 mM, 0.1 mM, or 20 µM. CP and CPK were necessary for these experiments as determined experimentally by their effect on the tension-Ca++ relation, which was saturated for CP ≥ 14.5 mM. This was interpreted to mean that sufficient CP was present to effectively buffer MgATP intracellularly. Decreasing MgATP shifts the tension-pCa curve to higher pCa (-log Ca++) so that, for half-maximal tension: pCa1/2 = 4.5 for MgATP = 2 mM, pCa1/2 = 5.1 for MgATP = 0.1 mM, and pCa1/2 = 5.8 for MgATP = 20 µM; maximum isometric tension is the same in all cases, however. If MgATP was decreased to 1 µM, tension at Ga++ > 10–8 M was 84% of the maximum Ca-+-activated tension in 2 mM MgATP and increased only slightly to 90% for pCa = 4.5. Weber (1970, In The Physiology and Biochemistry of Muscle as Food, Volume 2, E. J. Briskey, R. G. Cassens, and B. B. Marsh, University of Wisconsin Press, Madison, Wis.), using similar solutions, observed similar shifts in half-maximal calcium activation of rabbit myofibril ATPase rates. In explanation, Weber and Bremel (1971, In Contractility of Muscle Cells and Related Processes, R. J. Podolsky, editor, Prentice-Hall, Inc., Englewood Cliffs, N.J.; Bremel and Weber, 1972, Nat. New Biol., 238:97) have described a mechanism whereby, at low ATP, "rigor complexes" are formed between myosin and thin filament actin and, in turn, alter the calcium affinity of one class of the two Ca++-binding sites on troponin, so that the thin filament is "turned on" for contraction at lower Ca++ levels. Tension data from skinned fibers substantially supports this hypothesis. A stability constant for CaEGTA of 2.62 x 1010 M–1 was determined, with the help of F. N. Briggs, in solutions similar to those used for skinned fibers and was the same for 100 and 300 mM KCl.

Response of compressed skinned skeletal muscle fibers to conditions that simulate fatigue

1997 ◽  
Vol 82 (4) ◽  
pp. 1297-1304 ◽  
Author(s):  
Kathryn H. Myburgh ◽  
Roger Cooke
Keyword(s):  
Skeletal Muscle ◽  
Lattice Spacing ◽  
Atp Hydrolysis ◽  
Muscle Fibers ◽  
Isometric Tension ◽  
Skinned Fibers ◽  
Skinned Muscle ◽  
Skeletal Muscle Fibers ◽  
Myosin Subunits ◽  
Osmotic Compression

Myburgh, Kathryn H., and Roger Cooke. Response of compressed skinned skeletal muscle fibers to conditions that simulate fatigue. J. Appl. Physiol. 82(4): 1297–1304, 1997.—During fatigue, muscles become weaker, slower, and more economical at producing tension. Studies of skinned muscle fibers can explain some but not all of these effects, and, in particular, they are less economical in conditions that simulate fatigue. We investigated three factors that may contribute to the different behavior of skinned fibers. 1) Skinned fibers have increased myofilament lattice spacing, which is reversible by osmotic compression. 2) A myosin subunit becomes phosphorylated during fatigue. 3) Inosine 5′-monophosphate (IMP) accumulates during fatigue. We tested the response of phosphorylated and unphosphorylated single skinned fibers (isometric tension, contraction velocity, and adenosinetriphosphatase activity) to changes in lattice spacing (0–5% dextran) and IMP (0–5 mM) in the presence of altered concentrations of Pi (3–25 mM), H+ (pH 7–6.2), and ADP (0–5 mM). The response of maximally activated skinned fibers to the direct metabolites of ATP hydrolysis is not altered by osmotic compression, phosphorylating myosin subunits, or increasing IMP concentration. These factors, therefore, do not explain the discrepancy between intact and skinned fibers during fatigue.

pH dependence of myosin binding-induced activation of the thin filament in cardiac myocytes and skeletal fibers

1996 ◽  
Vol 270 (3) ◽  
pp. H1008-H1014 ◽  
Author(s):  
J. M. Metzger
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Myocytes ◽  
Thin Filament ◽  
Ph Dependence ◽  
Muscle Fibers ◽  
Isometric Tension ◽  
Experimental Conditions ◽  
Skeletal Muscle Fibers ◽  
Myosin Binding ◽  
Fast Twitch

The pH dependence of myosin binding-induced thin filament activation was determined in permeabilized cardiac myocytes and slow- and fast-twitch single skeletal muscle fibers by experimental lowering of [MgATP] in the Ca(2+)-free solutions bathing the permeabilized preparations. As the pS (where S is [MgATP] and pS is -log[MgATP]) was increased from 3.0 to 8.0, isometric tension increased to a peak value in the pS range of 4.9-5.3. At pH 7.00, the transition from the relaxed to the activated rigor state was steep in cardiac myocytes [Hill value (nH) = 21.2 +/- 3.1 (SE)] and due to the apparent effect of strongly bound cross bridges to cooperatively activate the thin filament in the absence of added Ca2+. At pH 6.20, the steepness of the tension-pS relationship was markedly reduced (nH = 6.1 +/- 1.0) and the midpoint of the relationship (pS50) was shifted to higher pS values in cardiac myocytes. In comparison, reduced pH had no effect on the steepness or position of the tension-pS relationship in single slow- or fast-twitch skeletal muscle fibers. These findings suggest that myosin binding-induced activation of the thin filament is pH dependent in cardiac myocytes but not in skeletal muscle fibers under these experimental conditions in which Ca2+ is absent.

Eugenol-induced contractions of saponin-skinned fibers are inhibited by heparin or by a ryanodine receptor blocker

2005 ◽  
Vol 83 (12) ◽  
pp. 1093-1100 ◽  
Author(s):  
Marco S. Lofrano-Alves ◽  
Edson L. Oliveira ◽  
Carlos E.N. Damiani ◽  
Ilana Kassouf-Silva ◽  
Rosalvo T.H. Fogaça
Keyword(s):  
Ryanodine Receptor ◽  
Rana Catesbeiana ◽  
Ryanodine Receptors ◽  
Muscle Fibers ◽  
Ruthenium Red ◽  
Muscle Contractions ◽  
Skinned Fibers ◽  
Receptor Blocker ◽  
Release Channel ◽  
Skinned Muscle

The effects of eugenol on the sarcoplasmic reticulum (SR) and contractile apparatus of chemically skinned skeletal muscle fibers of the frog Rana catesbeiana were investigated. In saponin-skinned fibers, eugenol (5 mmol/L) induced muscle contractions, probably by releasing Ca2+ from the SR. The Ca2+-induced Ca2+ release blocker ruthenium red (10 μmol/L) inhibited both caffeine- and eugenol-induced muscle contractions. Ryanodine (200 μmol/L), a specific ryanodine receptor/Ca2+ release channel blocker, promoted complete inhibition of the contractions induced by caffeine, but only partially blocked the contractions induced by eugenol. Heparin (2.5 mg/mL), an inositol 1,4,5-trisphosphate (InsP3) receptor blocker, strongly inhibited the contractions induced by eugenol but had only a small effect on the caffeine-induced contractions. Eugenol neither altered the Ca2+ sensitivity nor the maximal force in Triton X-100 skinned muscle fibers. These data suggest that muscle contraction induced by eugenol involves at least 2 mechanisms of Ca2+ release from the SR: one related to the activation of the ryanodine receptors and another through a heparin-sensitive pathway.

scholarly journals Longitudinal Impedance of Skinned Frog Muscle Fibers

1974 ◽  
Vol 63 (5) ◽  
pp. 625-638 ◽  
Author(s):  
Bert A. Mobley ◽  
J. Leung ◽  
R. S. Eisenberg
Keyword(s):  
Muscle Fibers ◽  
Longitudinal Section ◽  
Skinned Fibers ◽  
Stray Capacitance ◽  
Chemical Methods ◽  
Semitendinosus Muscle ◽  
Skinned Muscle ◽  
Skinned Muscle Fibers ◽  
Longitudinal Impedance ◽  
Zero Phase

Longitudinal impedance of skinned muscle fibers was measured with extracellular electrodes and an oil gap method in which a central longitudinal section of fiber is insulated by oil while the ends of the fiber are bathed in conducting pools of relaxing solution. Intact single fibers were isolated from frog semitendinosus muscle and the sarcolemma removed either by mechanical or chemical methods. Stray capacitance across the oil gap was measured after each experiment and its admittance subtracted from the admittance of the fiber and oil gap. Effects of impedance at the ends of the fiber were eliminated by measuring the impedance with two lengths of fiber in the oil gap and subtracting the impedance at the shorter length from that at the longer length. Longitudinal impedance so determined for mechanically and chemically skinned fibers exhibited zero phase shift from 1 to 10,000 Hz, i.e., the longitudinal impedance of skinned fibers is purely resistive. If we assume that our skinned fibers are a model of the sarcoplasm of muscle, we conclude that the equivalent circuit of the sarcoplasm is a resistor.

Mechanism of action of 2,3-butanedione monoxime on contracture during metabolic inhibition

1994 ◽  
Vol 267 (1) ◽  
pp. H100-H108 ◽  
Author(s):  
R. J. Hajjar ◽  
J. S. Ingwall ◽  
J. K. Gwathmey
Keyword(s):  
Frequency Dependence ◽  
Creatine Phosphate ◽  
Metabolic Inhibition ◽  
Skinned Fibers ◽  
Cross Bridge ◽  
Skinned Muscle ◽  
Skinned Muscle Fibers ◽  
Weak Binding ◽  
Butanedione Monoxime ◽  
Cross Bridges

The effect of 2,3-butanedione monoxime (BDM) was investigated during metabolic inhibition (MI) in papillary muscles. MI caused a rapid decrease in developed force and an increase in resting force, along with a decrease in ATP and creatine phosphate (CrP). Addition of BDM before MI decreased maximal contracture force, increased the time, and slowed the rates of ATP and CrP depletion. BDM addition at the peak of contracture did not alter the level of developed contracture. To simulate MI in skinned fiber preparations, we decreased the [MgATP] at pCa 8. [MgATP] of 3.2 microM resulted in a large increase in resting force. The force developed was less in BDM-pretreated muscles. Addition of 10 mM BDM at steady state did not affect force development ([MgATP] 3.2 microM, pCa 8.0). Cross-bridge kinetics in intact and skinned muscle fibers with and without BDM in the presence and absence of MI were studied. Intact muscles with MI revealed no frequency dependence at peak contracture and had elevated stiffness values. In skinned fibers, at [MgATP] of 3.2 microM and pCa of 8, no frequency dependence was observed, and the muscles had similarly high stiffness values. BDM pretreatment in both intact and skinned fibers inhibited rigor formation. These results suggest that BDM inhibits cross-bridge formation in the weak-binding state or actively cycling cross bridges.

scholarly journals Nonparallel isometric tension response of rabbit soleus skinned muscle fibers to magnesium adenosine triphosphate and magnesium inosine triphosphate.

1979 ◽  
Vol 74 (2) ◽  
pp. 261-274 ◽  
Author(s):  
B Krasner
Keyword(s):  
Steady State ◽  
Ionic Strength ◽  
Adenosine Triphosphate ◽  
Soleus Muscle ◽  
Muscle Fibers ◽  
Isometric Tension ◽  
Maximum Tension ◽  
Skinned Muscle ◽  
Tension Response ◽  
Skinned Muscle Fibers

The isometric tension response of single "skinned' rabbit soleus muscle fibers to MgATP and McITP in the absence of calcium was studied. [MgATP] or [MgITP] was varied in solutions of ionic strength 0.30 and temperature 20 degrees C. Steady-state tension that developed in MgATP or MgITP solutions was a biphasic bell-shaped function of log [MgATP] or log [MgITP] which increased from zero to maximum tension and then declined again to zero. Analysis of the data showed that, under comparable ionic conditions, percent tension vs. log [MgATP] and percent tension vs. log [MgITP] curves are not parallel. Instead, the percent tension vs. log [MgITP] curve is much broader. Additionally, under comparable ionic conditions maximum tension in MgITP solutions was higher than in MgATP solutions. In addition, in MgATP solutions, pH, [K+], and excess ATP were varied. Raising pH from 7 to 8, [K+] from 46 mM to 200 mM, or decreasing excess ATP from 2 to 0.5 mM all increased maximum tension. None of these factors, however, influenced the shape or position of the percent tension vs. log [MgATP] curve.

scholarly journals Tension in Skinned Frog Muscle Fibers in Solutions of Varying Ionic Strength and Neutral Salt Composition

1973 ◽  
Vol 62 (5) ◽  
pp. 550-574 ◽  
Author(s):  
A. M. Gordon ◽  
R. E. Godt ◽  
S. K. B. Donaldson ◽  
C. E. Harris
Keyword(s):  
Ionic Strength ◽  
Muscle Fiber ◽  
Muscle Fibers ◽  
Isometric Tension ◽  
High Ionic Strength ◽  
Frog Muscle ◽  
Hypertonic Solution ◽  
Base Line ◽  
Neutral Salt ◽  
Skinned Muscle

The maximal calcium-activated isometric tension produced by a skinned frog single muscle fiber falls off as the ionic strength of the solution bathing this fiber is elevated declining to zero near 0.5 M as the ionic strength is varied using KCl. When other neutral salts are used, the tension always declines at high ionic strength, but there is some difference between the various neutral salts used. The anions and cations can be ordered in terms of their ability to inhibit the maximal calcium-activated tension. The order of increasing inhibition of tension (decreasing tension) at high ionic strength for anions is propionate- ≃ SO4-- < Cl- < Br-. The order of increasing inhibition of calcium-activated tension for cations is K+ ≃ Na+ ≃ TMA+ < TEA+ < TPrA+ < TBuA+. The decline of maximal calcium-activated isometric tension with elevated salt concentration (ionic strength) can quantitatively explain the decline of isometric tetanic tension of a frog muscle fiber bathed in a hypertonic solution if one assumes that the internal ionic strength of a muscle fiber in normal Ringer's solution is 0.14–0.17 M. There is an increase in the base-line tension of a skinned muscle fiber bathed in a relaxing solution (no added calcium and 3 mM EGTA) of low ionic strength. This tension, which has no correlate in the intact fiber in hypotonic solutions, appears to be a noncalcium-activated tension and correlates more with a declining ionic strength than with small changes in [MgATP], [Mg], pH buffer, or [EGTA]. It is dependent upon the specific neutral salts used with cations being ordered in increasing inhibition of this noncalcium-activated tension (decreasing tension) as TPrA+ < TMA+ < K+ ≃ Na+. Measurements of potentials inside these skinned muscle fibers bathed in relaxing solutions produced occasional small positive values (<6 mV) which were not significantly different from zero.

scholarly journals Influence of magnesium on chloride-induced calcium release in skinned muscle fibers.

1977 ◽  
Vol 69 (1) ◽  
pp. 17-35 ◽  
Author(s):  
E W Stephenson ◽  
R J Podolsky
Keyword(s):  
Calcium Release ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Ringer Solution ◽  
Skinned Fibers ◽  
Skinned Muscle ◽  
Skinned Muscle Fibers ◽  
Ca Uptake ◽  
45Ca Release ◽  
Net Release

Chloride-induced Ca release in skinned muscle fibers was studied by measuring isometric force transients and 45Ca loss from fiber to washout solutions. Skinned fibers prepared from muscles soaked in normal Ringer solution made large force transients in 120 mM Cl solution with 5 mM ATP and 1 mM Mg, but 3 mM Mg was inhibitory. Mg inhibition was antagonized by low temperature and by Cd, agents which slow active Ca uptake by the sarcoplasmic reticulum (SR). In low Mg++, Cl stimulated rapid 45Ca release from the SR in sufficient amounts to account for the force response. The increased 45Ca release was inhibited by EGTA, suggesting that release requires free Ca under these conditions. The 45Ca initially released was partially reaccumulated later. Reaccumulation was increased in higher Mg++. These results provide additional evidence that the Ca uptake rate is an important determinant of net release, and suggest that Mg++ acts primarily on this mechanism. Skinned fibers prepared from muscles soaked in low Cl solutions could give force responses to Cl solutions with 3 mM and 6 mM Mg. This observation suggests that the Cl stimulus varies with the [Cl] gradient across the internal membranes, and supports the hypothesis that applied Cl causes membrane depolarization.

scholarly journals Thin Filament-Reconstituted Skinned Muscle Fibers for the Study of Muscle Physiology

2011 ◽  
Vol 2011 ◽  
pp. 1-7 ◽  
Author(s):  
Sayaka Higuchi ◽  
Yoshikazu Tsukasaki ◽  
Norio Fukuda ◽  
Satoshi Kurihara ◽  
Hideaki Fujita
Keyword(s):  
Thin Filament ◽  
Muscle Fibers ◽  
Regulatory Proteins ◽  
Muscle Physiology ◽  
Sinusoidal Analysis ◽  
Skinned Muscle ◽  
Skinned Muscle Fibers ◽  
Actomyosin Interaction ◽  
Ideal System

We review the use of thin filament-reconstituted muscle fibers in the study of muscle physiology. Thin filament extraction and reconstitution protocol is a powerful technique to study the role of each component of the thin filament. It is also useful for studying the properties of genetically modified molecules such as actin and tropomyosin. We also review the combination of this protocol with sinusoidal analysis, which will provide a solid technique for determining the effect of regulatory proteins on actomyosin interaction and concomitant cross-bridge kinetics. We suggest that thin filament-reconstituted muscle fibers are an ideal system for studying muscle physiology especially when gene modifications of actin or tropomyosin are involved.

Effects on Ca(2+)-activated tension due to a synthetic NH2-terminal actin peptide in single skeletal muscle fibers

1995 ◽  
Vol 269 (5) ◽  
pp. C1193-C1199
Author(s):  
J. M. Metzger
Keyword(s):  
Skeletal Muscle ◽  
Thin Filament ◽  
Troponin I ◽  
Muscle Fibers ◽  
Isometric Tension ◽  
Specific Sequence ◽  
Tension Development ◽  
Terminal Domain ◽  
Skeletal Muscle Fibers ◽  
Inhibitory Region

Insight into the mechanism of force development in striated muscle will be provided by elucidating the specific regions of the actin molecule that interact with myosin and regulatory subunits of the thin filament during Ca(2+)-activated contraction. There is growing evidence that the acidic NH2-terminal domain of actin 1) may represent an important binding site for myosin and 2) may interact with the inhibitory region of troponin I. The purpose of this study was to determine the effects of a synthetic peptide corresponding to a specific sequence of the NH2-terminal domain of skeletal muscle actin on Ca(2+)-activated tension in chemically skinned single psoas skeletal muscle fibers. This study focused on the highly conserved Lys18-Arg28 amino acid sequence of actin, a region of native actin that is believed to interact with troponin I and myosin. The effects of synthetic actin peptide Lys18-Arg28 on tension development varied, depending on 1) the concentration of Ca2+ in the activating solutions and 2) the peptide concentration. At submaximal concentrations of Ca2+, isometric tension was reversibly potentiated in the presence of 100-500 microM synthetic actin peptide Lys18-Arg28. Importantly, scrambling the sequence of Lys18-Arg28 fully abolished the increase in Ca2+ sensitivity, providing evidence that the observed effects were specific to the sequence of peptide Lys18-Arg28. In contrast, maximum Ca(2+)-activated tension was inhibited by millimolar concentrations of Lys18-Arg28 and the scrambled peptide, indicating that this effect was nonspecific. The effect of peptide Lys18-Arg28 to increase the Ca2+ sensitivity of tension is not known but may be due to an effect of the actin peptide to alter thin filament activation, a possibility consistent with proposed interactions between this domain of actin and the inhibitory region of troponin I.

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