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  • 1
    Electronic Resource
    Electronic Resource
    Discrimination of Ca2+-ATPase activity of the sarcoplasmic reticulum from actomyosin-type ATPase activity of myofibrils in skinned mammalian skeletal muscle fibres: distinct effects of cyclopiazonic acid on the two ATPase activities (1991)
    Springer
    Journal of muscle research and cell motility 12 (1991), S. 355-365 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary We have developed a procedure to discriminate actomyosin-type ATPase activity from Ca2+-ATPase activity of sarcoplasmic reticulum (SR) in mechanically skinned fibres, determining simultaneously their Ca2+-induced tension and accompanying ATPase activity. When they were treated with an alkaline CyDTA-containing solution of low ionic strength which was reported to remove troponin C, the fibres showed a considerable amount of Ca2+-dependent ATPase activity, in spite of having little or no Ca2+-induced isometric tension. The residual ATPase activity is ascribed to the Ca2+-ATPase activity of SR, because it is completely abolished by 1% CHAPS treatment for 10 min. This conclusion is also supported by the finding that the Ca2+-dependence of the ATPase activity is very similar to that of Ca2+-ATPase of SR isolated from rabbit skeletal muscle, and that the estimated activity is consistent with the reported values of direct determinations. On the other hand, treatment with a detergent such as CHAPS or Triton X-100 removes SR activities (ATPase and Ca-uptake), leaving Ca2+-induced tension and actomyosin-type ATPase activity unchanged. This procedure indicated that the contribution of Ca2+-ATPase activity of SR may be minimal in total steady-state ATPase activity of mechanically skinned mammalian skeletal muscle fibres. Successive CyDTA and CHAPS treatments eliminated both Ca2+-induced tension and ATPase activity, which were recovered by the addition of troponin C. Using these procedures, we also examined the effect of cyclopiazonic acid (CPA) which was reported to be a specific inhibitor of Ca2+-ATPase of SR. Ca2+-ATPase activity of SR in skinned fibres was inhibited completely by 10 μm CPA and held to one-half by about 0.2 μm. This effect was only partially reversible. CPA at 10μ m or higher concentrations showed Ca2+-sensitizing action on myofibrils, which was readily reversible. CPA at 3μ m inhibited almost completely the Ca2+-ATPase activity of SR, while it had no effect on either actomyosin-type ATPase or isometric tension of myofibrils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01738590
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  • 2
    Electronic Resource
    Electronic Resource
    Stimulation by polyols of the two ryanodine receptor isoforms of frog skeletal muscle (1998)
    Springer
    Journal of muscle research and cell motility 19 (1998), S. 15-24 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract While the stimulating effect of concentrated salts on ryanodine receptor (RyR) is widely accepted in Ca2+-induced Ca2+ release (CICR) and [3H]ryanodine binding, the effect of non-ionic solutes on RyR is controversial. We investigated the effects of polyols on [3H]ryanodine binding to α- and β-RyR purified from bullfrog skeletal muscle, and on CICR from sarcoplasmic reticulum (SR) in a skinned frog skeletal muscle fibre. Addition of polyols (glucose, sucrose, sorbitol, glycerol and ethylene glycol) in submolar to molar concentrations to an isotonic salt medium increased dose-dependently Ca2+-activated [3H]ryanodine binding to α- and β-RyR of a similar magnitude. The increase is due to the rise in both apparent affinity (1/KD) and maximal numbers of binding sites (Bmax) for ryanodine. In addition to this stimulating effect, glucose sensitized both isoforms to Ca2+ in the Ca2+-activated reaction, which is distinct in mechanism(s) from caffeine. These stimulating effects of polyols were not observed unless some NaCl was present, which might explain the discrepancy among reported results. Consistent with these findings, polyols reversibly enhanced the rate of CICR from SR in skinned fibres with an increase in the Ca2+ sensitivity. The enhanced CICR was still sensitive to well-known modulators for CICR (Ca2+, Mg2+, adenine nucleotides and procaine), as with [3H]ryanodine binding. The results of this study reveal that polyols stimulate α- and β-RyR in frog skeletal muscle, bringing about increased CICR activity. The finding that the specific activity of polyols in stimulation of [3H]ryanodine binding was approximately proportional to their molecular weights leads us to discuss the possible modification of protein surface--water molecule interaction as an underlying mechanism
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005344108908
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  • 3
    Electronic Resource
    Electronic Resource
    Effect of quercetin on tension development by skinned fibres from frog skeletal muscle (1985)
    Springer
    Journal of muscle research and cell motility 6 (1985), S. 189-195 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary For proper interpretation of the results of drug-induced calcium release experiments with skinned fibres, it is necessary to know the direct effects of the drug on the contractile system. We examined the action of quercetin and its various solvents on mechanically skinned skeletal muscle fibre which is deprived of functioning sarcoplasmic reticulum by Triton X-100. Dimethyl sulphoxide (DMSO) at 1%, a solvent for quercetin, decreased reversibly Ca2+ sensitivity for the contractile system of frog skeletal muscle. Alcohol was similar to dimethyl sulphoxide. Polyethylene glycol was used as a solvent for quercetin, because the solvent at 1% was found to be inert to the pCa-tension relationship. Quercetin increased reversibly Ca2+ sensitivity of the contractile system with the unchanged maximum tension, the pCa-tension relationship being less steep. Since quercetin did not change calcium binding to troponin C from rabbit skeletal muscle, the effect may be due to modified molecular interactions which follow calcium binding to troponin C. The drug might also affect the interaction between troponin subunits. Because DMSO did not affect calcium binding to troponin C, either DMSO also modulates the interaction between troponin subunits and/or it modulates molecular interactions after calcium binding which lead to tension development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00713060
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  • 4
    Electronic Resource
    Electronic Resource
    ATP-ADP exchange reaction by fragmented sarcoplasmic reticulum from bullfrog skeletal muscle (1982)
    Springer
    Journal of muscle research and cell motility 3 (1982), S. 39-56 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ATP-ADP exchange reaction and its related partial reactions of fragmented sarcoplasmic reticulum from bullfrog skeletal muscle (frog FSR) were investigated and compared with those of rabbit FSR in order to understand the characteristics of calcium-activated ATPase (Ca2+-ATPase) of frog FSR. MgATP and magnesium-free ADP are substrates for the forward and backward reaction of the ATPase activity, respectively, which is consistent with the conclusion obtained with rabbit FSR. The ATP-ADP exchange rate of frog FSR increased sharply with an increase in Ca2+ concentration up to 3 µm, and then decreased as Ca2+ concentration increased from 3 µm to 100 µm, where the level of EP continued to increase. The exchange rate of frog FSR had a value similar to the overall ATPase activity at steady state. These results contrast with observations using rabbit FSR. The exchange rate of rabbit FSR, which is 10–30 times as high as the overall ATPase activity, reached a plateau at 1 µm Ca2+, and the decrease in the exchange rate with the increase in Ca2+ concentration was not observed until the concentration was greater than 30 µm, where the plateau of the ATPase activity was maintained. These results were discussed in reference to a possible ordered reaction sequence of ATP followed by calcium in the Ca2+-ATPase reaction. It is suggested thatk −5/k −6 for rabbit FSR at steady state should be larger than that for frog FSR by a factor of about 10 in the following reaction sequence. $$E.ATP.Ca EP + ADP E + P_i + ADP$$
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711879
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  • 5
    Electronic Resource
    Electronic Resource
    Characterization of increased Ca2+ efflux by quercetin from the sarcoplasmic reticulum in frog skinned skeletal muscle fibres (1986)
    Springer
    Journal of muscle research and cell motility 7 (1986), S. 142-150 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary To clarify further the characteristics of the Ca-releasing action of quercetin, we examined the effect of quercetin on Ca2+ efflux from the sarcoplasmic reticulum without Ca uptake activity by omission of ATP in the presence of a high concentration (10 mm EGTA) of Ca2+ buffer, using mechanically skinned fibres from frog skeletal muscles. Quercetin increases the rate of Ca release in the presence of Ca2+ and shifts the relationship between Ca2+ concentration and the rate of Ca release to a lower range of Ca2+ concentrations. AMP potentiates the effect of quercetin. Mg2+ and procaine decrease the rate of Ca release in the presence of quercetin. These findings indicate that quercetin is very similar to caffeine; in fact, experiments confirmed that quercetin shares the site(s) of action with caffeine. Subsequent findings, however, suggest that the mechanism of the drug-induced Ca release is not as simple as expected with caffeine which may increase the affinity for Ca2+ of the ‘Ca2+-induced Ca-release’ mechanism, and that drugs, Ca2+ and nucleotide interact with one another in a more complex way to open the gate for Ca release. In the presence of 10 mm EGTA quercetin also causes Ca release in the virtual absence of Ca2+ if a sufficient amount of AMP is present, and the rate of Ca release in the presence of 1.55 μm Ca2+ showed different dependence on AMP concentration with and without quercetin. A higher concentration of Mg2+ is required in the presence of AMP than in the absence of AMP in order to eliminate Ca release by quercetin.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01753415
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison of properties of Ca2+ release channels between rabbit and frog skeletal muscles (1999)
    Springer
    Molecular and cellular biochemistry 190 (1999), S. 191-201 
    Details
    ISSN: 1573-4919
    Keywords: Ca2+ release ; frog ; rabbit ; ryanodine receptor ; skeletal muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Biochemical investigation of Ca2+ release channel proteins has been carried out mainly with rabbit skeletal muscles, while frog skeletal muscles have been preferentially used for physiological investigation of Ca2+ release. In this review, we compared the properties of ryanodine receptors (RyR), Ca2+ release channel protein, in skeletal muscles between rabbit and frog. While the Ryr1 isoform is the main RyR of rabbit skeletal muscles, two isoforms, α- and β-RyR which are homologous to Ryr1 and Ryr3 isoforms in mammals, respectively, coexist as a homotetramer in a similar amount in frog skeletal muscles. The two isoforms in an isotonic medium show very similar property in [3H]ryanodine binding activity which is parallel to Ca2+-induced Ca2+ release (CICR) activity, and make independent contributions to the activities of the sarcoplasmic reticulum. CICR and [3H]ryanodine binding activities of rabbit and frog are qualitatively similar in stimulation by Ca2+, adenine nucleotide and caffeine, however, they showed the following quantitative differences. First, rabbit RyR showed higher Ca2+ affinity than the frog. Second, rabbit RyR showed higher activity in the presence of Ca2+ alone with less stimulation by adenine nucleotide than the frog. Third, rabbit RyR displayed less enhancement of [3H]ryanodine binding by caffeine in spite of having a similar magnitude of Ca2+ sensitization than the frog, which may explain the occasional difficulty by researchers to demonstrate caffeine contracture with mammalian skeletal muscles. Finally, but not least, rabbit RyR still showed marked inhibition of [3H]ryanodine binding in the presence of high Ca2+ concentrations in the 1 M NaCl medium, while frog RyR showed disinhibition. Other matters relevant to Ca2+ release were also discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006903401123
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  • 7
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    A tryptophan residue in the caffeine-binding site of the ryanodine receptor regulates Ca2+ sensitivity (2018)
    Springer Nature
    Details
    Publication Date: 2018-07-23
    Electronic ISSN: 2399-3642
    Topics: Biology
    Published by Springer Nature
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  • 8
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    In Vitro Models of GJB2-Related Hearing Loss Recapitulate Ca2+ Transients via a Gap Junction Characteristic of Developing Cochlea (2016)
    Cell Press
    Details
    Publication Date: 2016-12-01
    Print ISSN: 2213-6711
    Topics: Biology , Medicine
    Published by Cell Press
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  • 9
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    Effect of Local Anesthetics on Calcium Activated ATPase and Its Partial Reaction with Fragmented Sarcoplasmic Reticulum from Bullfrog and Rabbit Skeletal Muscle1 (1982)
    Oxford University Press
    Details
    Publication Date: 1982-01-01
    Print ISSN: 0021-924X
    Electronic ISSN: 1756-2651
    Topics: Biology , Chemistry and Pharmacology
    Published by Oxford University Press on behalf of Japanese Biochemical Society.
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  • 10
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    Heat Production and Proton Release during the ATP-Driven CaUptake by Fragmented Sarcoplasmic Reticulum from Bullfrog and Rabbit Skeletal Muscle12 (1980)
    Oxford University Press
    Details
    Publication Date: 1980-10-01
    Print ISSN: 0021-924X
    Electronic ISSN: 1756-2651
    Topics: Biology , Chemistry and Pharmacology
    Published by Oxford University Press on behalf of Japanese Biochemical Society.
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