Acetylcholinesterase in membrane fractions derived from sarcotubular system of skeletal muscle: presence of monomeric acetylcholinesterase in sarcoplasmic reticulum and transverse tubule membranes

1987 ◽  
Vol 10 (3) ◽  
pp. 329-338 ◽  
Author(s):  
Cecilio J. Vidal ◽  
Encarnación Muñoz-Delgado ◽  
Asunción Yagüe-Guirao
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Transverse Tubule ◽  
Sarcotubular System

Calmodulin and Excitation-Contraction Coupling

Physiology ◽  
2000 ◽  
Vol 15 (6) ◽  
pp. 281-284 ◽  
Author(s):  
Susan L. Hamilton ◽  
Irina Serysheva ◽  
Gale M. Strasburg
Keyword(s):  
Skeletal Muscle ◽  
Ion Channels ◽  
Sarcoplasmic Reticulum ◽  
Release Channel ◽  
Excitation Contraction Coupling ◽  
Transverse Tubule ◽  
Contraction Coupling ◽  
Voltage Dependent ◽  
Important Regulator ◽  
Precise Role

Excitation-contraction coupling in cardiac and skeletal muscle involves the transverse-tubule voltage-dependent Ca2+ channel and the sarcoplasmic reticulum Ca2+ release channel. Both of these ion channels bind and are modulated by calmodulin in both its Ca2+-bound and Ca2+-free forms. Calmodulin is, therefore, potentially an important regulator of excitation-contraction coupling. Its precise role, however, has not yet been defined.

Mechanisms of stimulated 45Ca efflux in skinned skeletal muscle fibers

1987 ◽  
Vol 65 (4) ◽  
pp. 632-641 ◽  
Author(s):  
Elizabeth W. Stephenson
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Isometric Force ◽  
Signal Transmission ◽  
Transverse Tubules ◽  
Transverse Tubule ◽  
Ion Gradients ◽  
Charge Movements ◽  
Stimulation Of

Excitation–contraction (E–C) coupling in skeletal muscle can be studied in skinned fibers by direct assay of 45Ca efflux and simultaneous isometric force, under controlled conditions. Recent work provides evidence that such studies can address major current questions about the mechanisms of signal transmission between transverse tubules and sarcoplasmic reticulum and sarcoplasmic reticulum calcium release, as well as operation of the sarcoplasmic reticulum active Ca transport system in situ. Stimulation by imposed ion gradients at constant [K+][Cl−] product results in 45Ca release with two components: a large Ca2+-dependent efflux, responsible for contractile activation, and a small Ca2+-insensitive efflux. The Ca2+-insensitive stimulation is sustained, consistent with sustained depolarization, and appears to gradate the Ca2+-dependent stimulation; this component is likely to reflect intermediate steps in E–C coupling. Several lines of evidence suggest that the depolarizing stimulus acts on the transverse tubules. It is inhibited by the impermeant glycoside ouabain applied before skinning, which should specifically inhibit polarization of subsequently sealed transverse tubules. Sealed polarized transverse tubules also are the only plausible target for stimulation of 45Ca release by monensin and gramicidin D, which can rapidly dissipate Na+ and K+ gradients; a protonophore and the K+-specific ionophore valinomycin are ineffective, lonophore stimulation is prevented by the permeant glycoside digitoxin; it is also highly Ca2+ dependent. Stimulation of 45Ca release by imposed ion gradients is potentiated by perchlorate, which potentiates charge movements and activation in intact fibers, and is inhibited selectively in highly stretched fibers, presumably by transverse tubule – sarcoplasmic reticulum uncoupling. These results relate the Ca2+-dependent sarcoplasmic reticulum efflux channel to the physiological transverse tubule – sarcoplasmic reticulum coupling pathway, which also could involve Ca2+.

scholarly journals Ca2+ dependence of transverse tubule-mediated calcium release in skinned skeletal muscle fibers.

1986 ◽  
Vol 87 (2) ◽  
pp. 271-288 ◽  
Author(s):  
P Volpe ◽  
E W Stephenson
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Muscle Fibers ◽  
Transverse Tubule ◽  
Force Development ◽  
Skeletal Muscle Fibers ◽  
Gramicidin D ◽  
45Ca Efflux ◽  
Stimulation Of

Isometric force and 45Ca efflux from the sarcoplasmic reticulum were measured at 19 degrees C in frog skeletal muscle fibers skinned by microdissection. After Ca2+ loading, application of the ionophores monensin, an Na+(K+)/H+ exchanger, or gramicidin D, an H+ greater than K+ greater than Na+ channel-former, evoked rapid force development and stimulated release of approximately 30% of the accumulated 45Ca within 1 min, whereas CCCP (carbonyl cyanide pyruvate p-trichloromethoxyphenylhydrazone), a protonophore, and valinomycin, a neutral, K+-specific ionophore, did not. When monensin was present in all bathing solutions, i.e., before and during Ca2+ loading, subsequent application failed to elicit force development and to stimulate 45Ca efflux. 5 min pretreatment of the skinned fibers with 50 microM digitoxin, a permeant glycoside that specifically inhibits the Na+,K+ pump, inhibited monensin and gramicidin D stimulation of 45Ca efflux; similar pretreatment with 100 microM ouabain, an impermeant glycoside, was ineffective. Monensin stimulation of 45Ca efflux was abolished by brief pretreatment with 5 mM EGTA, which chelates myofilament-space calcium. These results suggest that: monensin and gramicidin D stimulate Ca2+ release from the sarcoplasmic reticulum that is mediated by depolarization of the transverse tubules, which seal off after sarcolemma removal and form closed compartments; a transverse tubule membrane potential (myofilament space-negative) is maintained and/or established by the operation of the Na+,K+ pump in the transverse tubule membranes and is sensitive to the permeant inhibitor digitoxin; the transverse tubule-mediated stimulation of 45Ca efflux appears to be entirely Ca2+ dependent.

scholarly journals Effect of endurance exercise on the Ca2+ pumps from transverse tubule and sarcoplasmic reticulum of rabbit skeletal muscle

2004 ◽  
Vol 97 (2) ◽  
pp. 467-474 ◽  
Author(s):  
Viola Becker ◽  
Hugo González-Serratos ◽  
Rocío Álvarez ◽  
Michael Bäermann ◽  
Claudine Irles ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Transition Temperature ◽  
Sarcoplasmic Reticulum ◽  
Endurance Exercise ◽  
Structural Changes ◽  
Muscular Activity ◽  
Fast Skeletal Muscle ◽  
Scanning Calorimetry ◽  
Transverse Tubule ◽  
Pump Activity

The sarcoplasmic reticulum (SR) Ca2+ pump is the main homeostatic regulatory mechanism in fast skeletal muscle that maintains intracellular Ca2+ concentration ([Ca2+]i) at the nanomolar level at rest. The transverse tubule (TT) Ca2+ pump transports cytosolic Ca2+ to the extracellular space. During prolonged muscular activity, [Ca2+]i may increase. TT and SR isolated microsomal vesicles were highly purified, and the purity was checked by immunoblotting. The present study shows the effects of endurance exercise on the activities and structures of the TT and SR Ca2+ pumps of fast skeletal muscle from rabbit at rest. The Ca2+ pump activity increased manifolds in TT but did not change in SR. The protein denaturalization profiles obtained by differential scanning calorimetry showed 1) a shift in the transition temperature and an increase in the enthalpy of the TT Ca2+ pump and 2) a significant change in the transition temperature of the SR Ca2+ pump Ca2+-binding domain. We conclude that the TT Ca2+ pump activity was upgraded in association with structural changes to handle the changes in [Ca2+]i and TT lumen Ca2+ concentration that occur during endurance exercise.

scholarly journals Restricted Distribution of mRNAs Encoding a Sarcoplasmic Reticulum or Transverse Tubule Protein in Skeletal Myofibers

2005 ◽  
Vol 53 (2) ◽  
pp. 217-227 ◽  
Author(s):  
Marja Nissinen ◽  
Tuula Kaisto ◽  
Paula Salmela ◽  
Juha Peltonen ◽  
Kalervo Metsikkö
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Potential Role ◽  
Sr Protein ◽  
Transverse Tubule ◽  
Marker Proteins ◽  
Flexor Digitorum Brevis ◽  
Flexor Digitorum ◽  
Mrna Targeting

Calsequestrin (CSQ) and dihydropyridine receptor (DHPR) are muscle cell proteins that are directed into the endoplasmic reticulum (ER) during translation. The former is subsequently found in the sarcoplasmic reticulum (SR) and the latter in the transverse tubule membrane. To elucidate the potential role of mRNA targeting within muscle cells, we have analyzed the localization of CSQ and DHPR proteins and mRNAs in primary cultured rat myotubes, in skeletal muscle cryosections, and in isolated flexor digitorum brevis muscle fibers. In the myotube stage of differentiation, the mRNAs distributed throughout the cell, mimicking the distribution of the endogenous ER marker proteins. In the adult skeletal myofibers, however, both CSQ and DHPRα1 transcripts located perinuclearly and in cross-striations flanking Z lines beneath the sarcolemma, a distribution pattern that sharply contrasted the interfibrillar distribution of typical ER proteins. Interestingly, all nuclei of the myofibers were transcriptionally active. In summary, the mRNAs encoding either a resident SR protein or a transverse tubule protein were located beneath the sarcolemma, implying that translocation of the respective proteins to the lumen of ER takes place at this location.

Effects of Propofol on Calcium sup 2+ Regulation by Malignant Hyperthermia-susceptible Muscle Membranes 

1995 ◽  
Vol 82 (5) ◽  
pp. 1274-1282 ◽  
Author(s):  
Bradley R. Fruen ◽  
James R. Mickelson ◽  
Timothy J. Roghair ◽  
Lynn A. Litterer ◽  
Charles F. Louis
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Malignant Hyperthermia ◽  
Ryanodine Receptor ◽  
Membrane Vesicles ◽  
Dihydropyridine Receptor ◽  
Muscle Membrane ◽  
Inhalation Anesthetics ◽  
Transverse Tubule ◽  
Malignant Hyperthermia Susceptible

Background The effects of inhalation anesthetics on Ca2+ regulation in malignant hyperthermia-susceptible skeletal muscle are considered to be responsible for triggering malignant hyperthermia. The intravenous anesthetic propofol does not trigger malignant hyperthermia in susceptible patients or experimental animals, suggesting that there are important differences between the effects of propofol and the effects of inhalation anesthetics on Ca2+ regulation in malignant hyperthermia-susceptible muscle. Understanding these differences may help to clarify the mechanisms responsible for triggering malignant hyperthermia. Methods To investigate the effects of propofol on Ca2+ regulation by malignant hyperthermia-susceptible skeletal muscle, we determined its effects on the membrane channels and pumps that control myoplasmic Ca2+ concentrations: the sarcoplasmic reticulum ryanodine receptor, the transverse tubule dihydropyridine receptor, and the sarcoplasmic reticulum Ca(2+)-adenosine triphosphatase (Ca(2+)-ATPase). Terminal cisternae-derived sarcoplasmic reticulum vesicles enriched in the junctional proteins of the sarcoplasmic reticulum and the transverse tubule membranes were isolated from the muscle of malignant hyperthermia-susceptible and normal pigs. Ca2+ flux, Ca(2+)-ATPase, and ligand binding measurements on these isolated vesicle preparations were performed in the presence of varying propofol concentrations. Results Propofol (10-500 microM) had no effect on ryanodine receptor-mediated Ca2+ efflux from muscle membrane vesicles. Propofol (1-100 microM) also had no effect on sarcoplasmic reticulum vesicle [3H]ryanodine binding, whereas higher concentrations (200-300 microM) slightly inhibited [3H]ryanodine binding. Binding of the dihydropyridine receptor Ca2+ channel blocker [3H]PN200-110 to these preparations was inhibited by propofol (10-300 microM). Ca(2+)-ATPase activity was stimulated by 10-100 microM propofol but was inhibited by higher concentrations. In all cases, the effects of propofol on malignant hyperthermia-susceptible and normal membrane preparations were similar. Conclusions In contrast to malignant hyperthermia-triggering inhalation anesthetics, propofol does not stimulate malignant hyperthermia-susceptible or normal ryanodine receptor channel activity, even at > 100 times clinical concentrations. Effects on dihydropyridine receptor and Ca(2+)-ATPase function, however, are similar to the effects of inhalation anesthestics and require much lower concentrations of propofol. These findings, demonstrating that propofol does not activate ryanodine receptor Ca2+ channels, suggest a plausible explanation for why propofol does not trigger malignant hyperthermia in susceptible persons.

scholarly journals Sarcoplasmic-reticulum biogenesis in contraction-inhibited skeletal-muscle cultures

1992 ◽  
Vol 282 (2) ◽  
pp. 399-407 ◽  
Author(s):  
J H M Charuk ◽  
C Guerin ◽  
P C Holland
Keyword(s):  
Skeletal Muscle ◽  
Monoclonal Antibody ◽  
Sarcoplasmic Reticulum ◽  
Contractile Activity ◽  
Electrophoretic Analysis ◽  
High Energy ◽  
Muscle Fibres ◽  
Sarcotubular System ◽  
Muscle Cultures ◽  
Skeletal Muscle Fibres

We have previously shown that inhibition of the spontaneous contractile activity of cultured embryonic-chick skeletal-muscle fibres with tetrodotoxin (TTX) leads to decreased sarcoplasmic-reticulum Ca(2+)-transport rates and steady-state concentrations of the high-energy Ca(2+)-ATPase phosphoenzyme intermediate [Charuk & Holland (1983) Exp. Cell Res. 144, 143-157]. In the present study we used a monoclonal antibody to the Ca(2+)-ATPase to show that there is a decreased amount of enzyme accumulated by contraction-inhibited myotubes. Indirect immunofluorescence microscopy using the monoclonal antibody to the Ca(2+)-ATPase also revealed a disordered subcellular organization of the sarcotubular system in contraction-inhibited myotubes. The biogenesis of sarcoplasmic-reticulum proteins in TTX-paralysed myofibres was studied by labelling cells with [35S]methionine before isolation of the active Ca(2+)-pump membrane fraction. Protein turnover was selectively increased in that fraction from TTX-treated muscle cultures. Electrophoretic analysis and quantitative fluorography confirmed that decreased accumulation of the Ca(2+)-ATPase enzyme in contraction-inhibited myotubes was associated with increased turnover of this protein. The present results demonstrate that biogenesis of the sarcoplasmic-reticulum Ca(2+)-ATPase is regulated by the contractile activity of skeletal-muscle fibres.

Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

1977 ◽  
Vol 35 ◽  
pp. 576-577
Author(s):  
Joachim R. Sommer ◽  
Nancy R. Wallace
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Granular Material ◽  
Nuclear Envelope ◽  
Intracellular Calcium ◽  
Ruthenium Red ◽  
Threshold Concentration ◽  
Rapid Freezing ◽  
Frog Skeletal Muscle ◽  
Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

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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