Roles of extracellular and "trigger" calcium ions in excitation–contraction coupling in skeletal muscle

1982 ◽  
Vol 60 (4) ◽  
pp. 427-439 ◽  
Author(s):  
George B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Experimental Technique ◽  
Calcium Ions ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
New Findings ◽  
Membrane Bound ◽  
Stimulation Of

The experimental observations leading to the development of the "trigger" calcium hypothesis of excitation–contraction (E–C) coupling in skeletal muscle are discussed. Also considered in some detail are the experimental technique problems which interfere with the demonstration of this role for calcium. New findings reported are observations showing that in a zero Ca2+ solution after a delay of about 6–10 min, there is a stimulation of Ca2+ efflux. This is of sufficient size, even in very small toe muscles, to restore the twitch which previously had been reduced in size in the zero Ca2+. In studies with isolated fibre preparations it was demonstrated that depolarization contractures required extracellular Ca2+ ions for E–C coupling whereas twitches could use membrane-bound "trigger" calcium ions. Thus in zero Ca2+ the contractures were eliminated in a few seconds but twitch elimination took a few minutes. Finally, the roles in E–C coupling played by "trigger" and extracellular Ca2+ ions are summarized and discussed.

Extracellular divalent cations in excitation–contraction coupling: hypertonic solution effects

1982 ◽  
Vol 60 (4) ◽  
pp. 440-445
Author(s):  
Isao Oota ◽  
Isao Kosaka ◽  
Torao Nagai ◽  
Hideyo Yabu
Keyword(s):  
Skeletal Muscle ◽  
Divalent Cations ◽  
Muscle Fibers ◽  
Hypertonic Solution ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Skeletal Muscle Fibers ◽  
Membrane Bound

It is the purpose of this article to point out that the membrane-bound Ca plays an important role in excitation–contraction (E–C) coupling of skeletal muscle fibers and that other divalent cations are unable to substitute for this role of membrane-bound Ca.

Evidence for an essential role for calcium in excitation-contraction coupling in skeletal muscle

1964 ◽  
Vol 160 (981) ◽  
pp. 504-512 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fibre ◽  
Calcium Ions ◽  
Essential Role ◽  
Mechanical Response ◽  
Frog Heart ◽  
Muscle Fibres ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Spontaneous Action

The events and processes that link the electrical events which occur at the surface of a muscle fibre with the contractile process that takes place within the fibre, have been a continuing source of interest. Recently attention has been concentrated on the role played by calcium ions in linking these two events. As often happens in physiological investigations, the idea that calcium ions play an essential role in excitation-contraction coupling is not new. As long ago as 1883 Ringer demonstrated that the frog heart fails to contract and remains relaxed when calcium ions are absent from its perfusion fluid. Later it was shown that under this condition the rhythmic spontaneous action potentials of this preparation are still present in an only slightly modified form (Mines 1913). It was known at that time that the depolarization of the muscle fibre membrane is the electrical event responsible for initiating the mechanical response (Biedermann 1896) and although this point has been disputed from time to time, the evidence presently available makes it obvious that this is the case. One explanation of these observations is that the action potential or depolarization permits or promotes the movement of calcium ions from the surface to the interior of the muscle fibre and that these ions then initiate the mechanical response. A working hypothesis of this type was proposed by Sandow (1952). However, until fairly recently the only direct evidence supporting such an hypothesis was the demonstration by Heilbrunn & Wiercinski (1947) that calcium was the only physiologically occurring cation which would cause shortening when injected into bits of skeletal muscle fibres in low concentrations. This effect was later confirmed under more physiological conditions by Niedergerke (1955). Although there is considerable evidence of recent origin showing that calcium ions play an essential role in coupling in smooth and cardiac muscles, for the sake of brevity attention will be concentrated on skeletal muscle in the present discussion.

Anions that potentiate excitation-contraction coupling may mimic effect of phosphate on Ca2+ release channel

1994 ◽  
Vol 266 (6) ◽  
pp. C1729-C1735 ◽  
Author(s):  
B. R. Fruen ◽  
J. R. Mickelson ◽  
T. J. Roghair ◽  
H. L. Cheng ◽  
C. F. Louis
Keyword(s):  
Skeletal Muscle ◽  
Inorganic Phosphate ◽  
Inorganic Anions ◽  
Primary Site ◽  
Channel Activity ◽  
Release Channel ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Fold Stimulation ◽  
Stimulation Of

Perchlorate is one of a group of inorganic anions that potentiate excitation-contraction coupling in skeletal muscle. We have compared the effect of perchlorate on the sarcoplasmic reticulum (SR) Ca(2+)-release channel with the effect of inorganic phosphate (Pi), an anion which accumulates in skeletal muscle during exercise. Perchlorate and Pi (10-20 mM) stimulated Ca2+ release from SR vesicles 2- to 3-fold, respectively, and increased ryanodine binding to SR vesicles 1.5-fold. Stimulation of SR Ca(2+)-release channel activity by both perchlorate and Pi was maximal in the presence of micromolar Ca2+ and was associated with an increased affinity of the channel for ryanodine. Other anions known to potentiate muscle contraction (thiocyanate, iodide, and nitrate) also stimulated skeletal muscle SR Ca2+ release and ryanodine binding, as did the Pi analogue vanadate. However, none of the inorganic anions examined altered ryanodine binding to cardiac muscle SR. These results confirm that the SR Ca(2+)-release channel may be a primary site at which perchlorate and other potentiating anions affect skeletal muscle excitation-contraction coupling. In addition, these results demonstrate that the action of these anions on the SR Ca(2+)-release channel resembles that of Pi, a potential endogenous regulator of this channel.

scholarly journals Triadin Binding to the C-Terminal Luminal Loop of the Ryanodine Receptor is Important for Skeletal Muscle Excitation–Contraction Coupling

2007 ◽  
Vol 130 (4) ◽  
pp. 365-378 ◽  
Author(s):  
Sanjeewa A. Goonasekera ◽  
Nicole A. Beard ◽  
Linda Groom ◽  
Takashi Kimura ◽  
Alla D. Lyfenko ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Striated Muscle ◽  
Single Channel ◽  
Triple Mutant ◽  
Double Mutation ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Functional Studies

Ca2+ release from intracellular stores is controlled by complex interactions between multiple proteins. Triadin is a transmembrane glycoprotein of the junctional sarcoplasmic reticulum of striated muscle that interacts with both calsequestrin and the type 1 ryanodine receptor (RyR1) to communicate changes in luminal Ca2+ to the release machinery. However, the potential impact of the triadin association with RyR1 in skeletal muscle excitation–contraction coupling remains elusive. Here we show that triadin binding to RyR1 is critically important for rapid Ca2+ release during excitation–contraction coupling. To assess the functional impact of the triadin-RyR1 interaction, we expressed RyR1 mutants in which one or more of three negatively charged residues (D4878, D4907, and E4908) in the terminal RyR1 intraluminal loop were mutated to alanines in RyR1-null (dyspedic) myotubes. Coimmunoprecipitation revealed that triadin, but not junctin, binding to RyR1 was abolished in the triple (D4878A/D4907A/E4908A) mutant and one of the double (D4907A/E4908A) mutants, partially reduced in the D4878A/D4907A double mutant, but not affected by either individual (D4878A, D4907A, E4908A) mutations or the D4878A/E4908A double mutation. Functional studies revealed that the rate of voltage- and ligand-gated SR Ca2+ release were reduced in proportion to the degree of interruption in triadin binding. Ryanodine binding, single channel recording, and calcium release experiments conducted on WT and triple mutant channels in the absence of triadin demonstrated that the luminal loop mutations do not directly alter RyR1 function. These findings demonstrate that junctin and triadin bind to different sites on RyR1 and that triadin plays an important role in ensuring rapid Ca2+ release during excitation–contraction coupling in skeletal muscle.

Monoclonal Antibodies as Probes of Triad Structure and Excitation-Contraction Coupling in Skeletal Muscle

1990 ◽  
pp. 371-382 ◽  
Author(s):  
Mario S. Rosemblatt ◽  
Gonzalo Pérez ◽  
Bojena Antoniu ◽  
Evelyn Reilley ◽  
Noriaki Ikemoto
Keyword(s):  
Skeletal Muscle ◽  
Monoclonal Antibodies ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling
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