TETRAETHYLAMMONIUM-INDUCED CONTRACTIONS OF FROG'S SKELETAL MUSCLE: III. MECHANISM OF ACTION BY CALCIUM RELEASE

1967 ◽  
Vol 45 (5) ◽  
pp. 845-855 ◽  
Author(s):  
G. Beaulieu ◽  
G. B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Mechanism Of Action ◽  
Binding Sites ◽  
Neuromuscular Transmission ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Sartorius Muscle ◽  
Free Solution ◽  
Muscle Twitching ◽  
Solution Bathing

The effects of changes in the extracellular calcium concentration on the muscle 'twitching' response induced by tetraethylammonium of the frog's sartorius muscle were investigated. Decreasing the calcium concentration of a solution bathing the muscle increased the sensitivity of the muscle to TEA stimulation. However, with a sufficient calcium reduction (to 0.108 mM in most preparations) the muscles became completely insensitive to TEA stimulation. In contrast, calcium reduction resulted only in an increased muscle sensitivity to carbachol stimulation. Increasing the calcium concentration greatly decreased TEA sensitivity, and at 2.16 mM calcium a TEA-induced muscle 'twitching' response no longer could be produced. At this calcium concentration carbachol sensitivity was reduced but not eliminated and neuromuscular transmission was essentially unmodified. In studies with the toe muscle, it was found that TEA could restore the potassium-induced contracture that had been eliminated by soaking the muscle in a calcium-free solution. This effect of TEA was dependent upon the presence of a store of bound calcium in the muscle. These results are consistent with the hypothesis that TEA acts by releasing calcium from binding sites on the nerve endings, leading to an increased excitability and instability of these structures and resulting in the muscle twitching response. Other effects of TEA similar to those of increases in calcium are due to an increased level of ionized calcium at nerve and muscle membranes which also results from the release by TEA of calcium from membrane sites.

Dantrolene Sodium Can Increase or Attenuate Activity of Skeletal Muscle Ryanodine Receptor Calcium Release Channel

1996 ◽  
Vol 84 (6) ◽  
pp. 1368-1379 ◽  
Author(s):  
Thomas E. Nelson ◽  
Marina Lin ◽  
Gisele Zapata-Sudo ◽  
Roberto Takashi Sudo
Keyword(s):  
Skeletal Muscle ◽  
Muscle Relaxant ◽  
Binding Sites ◽  
Calcium Release ◽  
Vastus Lateralis Muscle ◽  
Calcium Release Channel ◽  
Dantrolene Sodium ◽  
Study Results ◽  
20 Nm ◽  
Reduced Activity

Background Dantrolene sodium (DS) is a direct-acting skeletal muscle relaxant whose only known action is to block calcium release from intracellular storage sites. The exact site of action for DS is unknown, but its efficacy in treating and preventing anesthetic-induced malignant hyperthermia (MH) is well established. Methods Single ryanodine (Ry1) receptor calcium release channels were incorporated into a planar lipid bilayer for electrophysiologic recording and for subsequent analysis of the channel's gating and conductance properties. The cellular effects of low DS concentrations were investigated by isometric contracture tension responses in biopsied MH human and dog muscle fascicles and in normal, single fibers from human vastus lateralis muscle. Results Two concentration-dependent DS effects on the isolated Ry1 receptor were discovered, suggesting at least two different binding sites. At nanomolar concentrations, DS activated the channel by causing three-to fivefold increases in open-state probability and dwell times. At micromolar concentrations, DS first increased then reduced activity in the channels; with the dominant effect being reduced activity. A 20 nm concentration of DS produced significant contracture tension in human muscle from one MH subject and caused potentiation of twitch in muscle from another MH patient. Halothane contracture in MH dog muscle was followed by an additional increase in tension when treated with 20 nm DS. Other investigations on chemically skinned, human fibers showed that calcium loaded in the sarcoplasmic reticulum was partially released by nM DS. Conclusions The study results suggest that at least two binding sites for DS exist on the Ry1 receptor calcium channel. A low-affinity (microM) site is associated with reduced channel gating and open-state dwell time and may relate to the established pharmacologic muscle relaxant effect of DS. The proposed high-affinity (nM) DS binding site activates the channel, producing Ca2+ release to the myoplasm, which, under environmentally adverse conditions, could damage genetically predisposed MH muscle. Such a phenomenon, if it occurs in DS treated MH patients, could generate a recrudescence of the syndrome.

Association of increased pHi with calcium ion release in skeletal muscle

1978 ◽  
Vol 234 (3) ◽  
pp. C110-C114 ◽  
Author(s):  
R. J. Connett
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ion ◽  
Calcium Release ◽  
Muscle Membrane ◽  
Sartorius Muscle ◽  
Ion Release ◽  
Extracellular Medium ◽  
Dantrolene Sodium ◽  
External Potassium ◽  
Frog Sartorius

The pH difference across the cell membrane of frog sartorius muscle cells was measured with the distribution of 5,5-dimethyl-2,4-oxazolidine-dione (DMO) as the marker. Depolarization of the muscles to values at or below the contraction threshold caused by elevating external potassium up to approximately 20 mM resulted in an internal alkalinization. The change was smaller with superthreshold depolarization (20--30 mM [K+]). The alkalinization was blocked by agents that block calcium release from the sarcoplasmic reticulum (procaine and dantrolene sodium). Other agents that cause calcium release (caffeine, theophylline, and quinine) were found to give alkalinization when tested at concentrations just below the contracture threshold. Increased acidification of the extracellular medium was associated with the internal alkalinization. The data were interpreted as indicating the presence of a calcium-stimulated H+ and/or OH- ion transport system in the muscle membrane.

scholarly journals Pharmacological distinction between dantrolene and ryanodine binding sites: evidence from normal and malignant hyperthermia-susceptible porcine skeletal muscle

1997 ◽  
Vol 326 (3) ◽  
pp. 847-852 ◽  
Author(s):  
Sanjay S. PALNITKAR ◽  
James R. MICKELSON ◽  
Charles F. LOUIS ◽  
Jerome PARNESS
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Binding Sites ◽  
Calcium Release ◽  
Drug Binding ◽  
Protein Patterns ◽  
Open Probability ◽  
Malignant Hyperthermia Susceptible ◽  
Discontinuous Sucrose Gradient ◽  
Muscle Types

Dantrolene inhibits and ryanodine stimulates calcium release from skeletal-muscle sarcoplasmic reticulum (SR), the former by an unknown mechanism, and the latter by activating the ryanodine receptor (RyR), the primary Ca2+-release channel of SR. Dantrolene is used to treat malignant hyperthermia (MH), a genetic predisposition to excessive intracellular Ca2+ release upon exposure to volatile anaesthetics. Porcine MH results from a point mutation in the SR RyR that alters the open probability of the channel, and is reflected in altered [3H]ryanodine binding parameters. Specific binding sites for [3H]dantrolene and [3H]ryanodine co-distribute on SR that has been isolated by discontinuous sucrose gradient centrifugation. If the two drug-binding sites are functionally linked, [3H]dantrolene binding might be affected both by pharmacological and by genetic modulators of the functional state of the RyR. Accordingly, we compared the characteristics of [3H]dantrolene binding to porcine malignant-hyperthermia-susceptible and normal-skeletal-muscle SR, and examined the effects of RyR modulators on [3H]dantrolene binding to these membranes. Additionally, the feasibility of separating the SR binding sites for [3H]dantrolene and [3H]ryanodine was investigated. No significant differences in [3H]dantrolene binding characteristics to SR membranes from the two muscle types were detected, and the Bmax ratio for [3H]dantrolene/[3H]ryanodine was 1.4(±0.1):1 in both muscle types. [3H]Dantrolene binding is unaffected by the RyR modulators caffeine, ryanodine, Ruthenium Red and calmodulin, and neither dantrolene nor azumolene have any effect on [3H]ryanodine binding. Additionally, distinct peaks of [3H]dantrolene and [3H]ryanodine binding are detected in SR membranes fractionated by linear sucrose centrifugation, although no differences in protein patterns are detected by SDS/PAGE or Western-blot analysis. We suggest that the binding sites for these two drugs are pharmacologically distinct, and may exist on separate molecules.

Fibrinogen Binding Is Independent of an Increase in Intracellular Calcium Concentration in Thrombin Degranulated Platelets

1995 ◽  
Vol 73 (02) ◽  
pp. 304-308 ◽  
Author(s):  
Fabio M Pulcinelli ◽  
James L Daniel ◽  
Silvia Riondino ◽  
Pier Paolo Gazzaniga ◽  
Leon Salganicoff
Keyword(s):  
Platelet Aggregation ◽  
Intracellular Calcium ◽  
Binding Sites ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Shape Change ◽  
Cytosolic Calcium ◽  
Calcium Mobilization ◽  
Induce Platelet Aggregation ◽  
Fibrinogen Binding

SummaryIn a suspension of thrombin degranulated platelets (TDP), ADP and epinephrine can induce platelet aggregation, whereas the synthetic agonist of the thromboxane/endoperoxide receptor U46619 causes only shape change. However, U46619 can enhance platelet aggregation induced by ADP and epinephrine. In this paper, we have measured fibrinogen binding in relation to phospholipase C(PLC) activation and calcium mobilization in TDP activated by ADP, epinephrine and U46619.ADP caused fibrinogen binding in TDP but neither activated PLC nor caused a calcium mobilization. The requirement for ADP in inducing exposure of fibrinogen binding sites was not absolute since the combination of epinephrine and U46619 produced an increase in fibrinogen binding. U46619 caused significant PLC activation and cytosolic calcium release but not fibrinogen binding. These results suggest that in TDP the exposure of fibrinogen binding sites, after agonist activation, is independent of both PLC activation and calcium mobilization.

Calcium Release and Spread Within the Sarcomere of Vertebrate Skeletal Muscle Fibers.

2000 ◽  
Vol 6 (S2) ◽  
pp. 94-95
Author(s):  
Stephen M. Baylor ◽  
Stephen Hollingworth
Keyword(s):  
Skeletal Muscle ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Muscle Fibers ◽  
Time Derivative ◽  
Free Calcium ◽  
Time To Peak ◽  
Skeletal Muscle Fibers ◽  
Free Calcium Concentration ◽  
Vertebrate Skeletal Muscle

Experiments were carried out to investigate excitation-contraction coupling in vertebrate skeletal muscle fibers. Single-dissected twitch fibers of frog muscle were injected with flourescent calcium (Ca) indicators, and fluorescence intensity (F) and changes in intensity (ΔF) were recorded during various stimulation protocols (16-22 °C). In fibers activated by an action potential, the low-affinity indicator furaptra was used to estimate the spatially-averaged change in myoplasmic free calcium concentration (ΔC[a]; peak value, 15-20 μM; time to peak, 4-5 ms). Δ[Ca], in combination with a kinetic model, was used to calculate the change in concentration of calcium bound to the principal myoplasmic Ca buffers (ATP, troponin, parvalbumin). The rate of Ca release from the sarcoplasmic reticulum (SR) was obtained from the time derivative of the estimated change in total myoplasmic calcium concentration, Δ[CaT] (= Δ[Ca] + Δ[CaATP] + Δ[CaTroponin] + Δ[CaParvalbumin]).

TETRAETHYLAMMONIUM-INDUCED CONTRACTIONS OF FROG'S SKELETAL MUSCLE: I. GENERAL CONSIDERATIONS

1967 ◽  
Vol 45 (5) ◽  
pp. 821-831 ◽  
Author(s):  
G. Beaulieu ◽  
G. B. Frank
Keyword(s):  
Latent Period ◽  
Neuromuscular Transmission ◽  
Nerve Endings ◽  
Induced Response ◽  
Sartorius Muscle ◽  
Muscle Twitching ◽  
Release Of Acetylcholine ◽  
Intramuscular Nerve ◽  
Unmyelinated Nerve ◽  
Indirect Stimulation

The mechanism for the production of the 'twitching' response induced by tetraethylammonium (TEA) of the frog's sartorius muscle was investigated. A linear relation was found between the log TEA concentration and the log of the latent period for the onset of the muscle response. The minimum latent period was 5 to 10 sec. Previously it was suggested that TEA caused the release of acetylcholine from intramuscular nerve endings to produce this response (13). The findings that blocking neuromuscular transmission by d-tubocurarine, by reduced extracellular calcium concentrations, or by repetitive indirect stimulation in the presence of hemicholinium also prevented the TEA-induced muscle 'twitching' response support the above suggestion. Exposing the preparation to procaine concentrations too low to block neuromuscular transmission blocked the TEA-induced response, indicating that this response was due to an effect of TEA on the unmyelinated nerve endings.

Erratum: Influence of temperature and external Ca2+ concentration upon dantrolene action on excitation–contraction coupling in frog skeletal muscle

1981 ◽  
Vol 59 (6) ◽  
pp. 607-612
Author(s):  
Toshiharu Oba
Keyword(s):  
Skeletal Muscle ◽  
Mechanism Of Action ◽  
Binding Sites ◽  
Threshold Current ◽  
Frog Skeletal Muscle ◽  
Temperature Dependent ◽  
Influence Of Temperature ◽  
Contraction Coupling ◽  
Mechanical Responses ◽  
Intracellular Stimulation

Effects of dantrolene (DAN) on electrical and mechanical responses in frog skeletal muscle were studied at various Ca2+ concentrations and temperatures to elucidate the mechanism of action of DAN. The following results were obtained. (a) Twitch tension of a DAN-injected fiber, elicited by intracellular stimulation, increased transiently and then decreased whereas extracellular DAN always depressed the tension. (b) Lowering the external Ca2+ concentration resulted in the potentiation of twitch tension. The addition of DAN, however, reduced the tension significantly (p < 0.05). (c) Extracellular DAN caused a transient reduction and subsequent elevation of the threshold current; however intracellular DAN caused only elevation of threshold. (d) DAN prevented the slow depolarization of the membrane in low Ca2+ medium. (e) These effects of the drug were temperature dependent, the effect being more pronounced at higher temperatures. These findings suggest that DAN may manifest its effects by replacement of Ca2+ from its binding sites on the membrane and that this occupation of the Ca2+ sites by DAN is temperature dependent.

Influence of temperature and external Ca2+ concentration upon dantrolene action on excitation–contraction coupling in frog skeletal muscle

1981 ◽  
Vol 59 (4) ◽  
pp. 358-363 ◽  
Author(s):  
Toshiharu Oba
Keyword(s):  
Skeletal Muscle ◽  
Mechanism Of Action ◽  
Binding Sites ◽  
Threshold Current ◽  
Frog Skeletal Muscle ◽  
Temperature Dependent ◽  
Influence Of Temperature ◽  
Contraction Coupling ◽  
Mechanical Responses ◽  
Intracellular Stimulation

Effects of dantrolene (DAN) on electrical and mechanical responses in frog skeletal muscle were studied at various Ca2+ concentrations and temperatures to elucidate the mechanism of action of DAN. The following results were obtained. (a) Twitch tension of a DAN-injected fiber, elicited by intracellular stimulation, increased transiently and then decreased whereas extracellular DAN always depressed the tension. (b) Lowering the external Ca2+ concentration resulted in the potentiation of twitch tension. The addition of DAN, however, reduced the tension significantly (p < 0.05). (c) Extracellular DAN caused a transient reduction and subsequent elevation of the threshold current; however intracellular DAN caused only elevation of threshold. (d) DAN prevented the slow depolarization of the membrane in low Ca2+ medium. (e) These effects of the drug were temperature dependent, the effect being more pronounced at higher temperatures. These findings suggest that DAN may manifest its effects by replacement of Ca2+ from its binding sites on the membrane and that this occupation of the Ca2+ sites by DAN is temperature dependent.

Electron Probe Analysis of Muscle

1982 ◽  
Vol 40 ◽  
pp. 398-401
Author(s):  
A. V. Somlyo ◽  
H. Shuman ◽  
A. P. Somlyo
Keyword(s):  
Skeletal Muscle ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Resting State ◽  
Binding Sites ◽  
Electron Probe ◽  
Frog Skeletal Muscle ◽  
Electron Probe Analysis ◽  
Probe Analysis

Electron probe analysis of frozen dried cryosections of frog skeletal muscle, rabbit vascular smooth muscle and of isolated, hyperpermeab1 e rabbit cardiac myocytes has been used to determine the composition of the cytoplasm and organelles in the resting state as well as during contraction. The concentration of elements within the organelles reflects the permeabilities of the organelle membranes to the cytoplasmic ions as well as binding sites. The measurements of [Ca] in the sarcoplasmic reticulum (SR) and mitochondria at rest and during contraction, have direct bearing on their role as release and/or storage sites for Ca in situ.

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