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  • 1
    Electronic Resource
    Electronic Resource
    Modulation of calcium sensitivity in guinea pig taenia coli: skinned fiber studies (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 997-1001 
    Details
    ISSN: 1420-9071
    Keywords: Myosin light chain kinase ; calcium ; c-AMP ; calmodulin ; smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01952120
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanical and biochemical characterization of the contraction elicited by a calcium-independent myosin light chain kinase in chemically skinned smooth muscle (1985)
    Springer
    Cellular and molecular life sciences 41 (1985), S. 1002-1006 
    Details
    ISSN: 1420-9071
    Keywords: Smooth muscle ; calcium ; myosin light chain kinase ; regulation of contraction ; ATPase ; mechanics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The contraction induced by a Ca2+-independent myosin light chain kinase (MLCK-) was characterized in terms of isometric force (Fo), immediate elastic recoil (SE), unloaded shortening velocity (Vus), shortening under a constant load and ATPase activity of chemically skinned smooth muscle preparations. These parameters were compared to those measured in a Ca2+-induced contraction to assess the nature of cross bridge interaction in the MLCK-induced contraction. Fo developed in chicken gizzard fibers as well as SE were similar in contractions elicited by either agent. Vus in the contraction induced by MLCK-(0.36 mg/ml) was similar though averaged 39.3±8.9% less than Vus induced by Ca2+ (1.6x10−6M) in the control fibers. Addition of Ca2+ (1.6x10−6M) to a contraction induced by MLCK-resulted in small increases in both Fo and Vus. Shortening under a constant load was similar for both types of contractions. The contraction induced by MLCK-was accompanied by an increased rate of ATP hydrolysis. The MLCK-induced contraction is thus kinetically similar though not identical to a contraction induced by Ca2+. We conclude that with respect to actin-myosin interaction, MLCK- and Ca2+-induced contractions are similar.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01952121
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Inhibition of TnI-TnC interaction and contraction of skinned muscle fibres by the synthetic peptide TnI [104–115] (1989)
    Springer
    Pflügers Archiv 414 (1989), S. 430-436 
    Details
    ISSN: 1432-2013
    Keywords: Contractile activation ; Skinned muscle fibres ; Calcium ions ; Peptides ; Troponin-I
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Circular dichroism was used to study the induction of helix in TnC or TnI-TnC by the TnI peptide [104–115] at various Ca2+ concentrations. The increase in negative ellipticity and pCa2+ values for the peptide-TnC complex, indicates that binding of the peptide to TnC, induces a small helical conformational change in TnC. This results in an increase in the Ca2+ binding constant and the pCa50 value required to induce 50% of Ca2+-dependent helix in TnC. The introduction of the peptide to a preformed mixture of TnI-TnC resulted in an increase in negative ellipticity and a decrease in the pCa50 and the apparent Ca2+ binding constant towards the values obtained for the TnI peptide-TnC complex and away from those of TnI-TnC. This demonstrates that the TnI peptide can successfully compete with TnI for TnC and thereby inhibit the TnI-TnC interaction. The addition of the TnI peptide to skinned rabbit psoas or porcine cardiac fibres resulted in the inhibition of the force development and a decrease in the pCa50 values required for 50% Ca2+ activation. The magnitude of the inhibition of tension development and the shift in the Ca2+ sensitivity for skinned cardiac muscle fibres was approximately half that observed with skeletal muscle fibres. In view of the CD findings, these skinned fibre results can be accounted for by the peptide inhibiting the TnI interaction with TnC. However, it is possible that the TnI peptide also has a direct inhibitory effect on TM-actin. Mastoparan, another TnC binding peptide, also inhibited the tension development in skinned skeletal and cardiac muscle fibres, but was much less efficient than the TnI peptide.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00585053
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Cyclic AMP inhibits contractility of detergent treated glycerol extracted cardiac muscle (1981)
    Springer
    Pflügers Archiv 391 (1981), S. 208-212 
    Details
    ISSN: 1432-2013
    Keywords: Myocardial contractility ; Troponin phosphorylation ; c-AMP ; Calcium ions ; Myocardial skinned fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Glycerinated myocardial fibres treated with a detergent (Lubrol WX) and suspended in ATP salt solution produce half maximum isometric tension at pCa 6.2 (at pH 6.7). After addition of cyclic AMP (1–100 μM), the pCa required for half maximum activation is 5.9. c-AMP in concentrations of 1–100 μM induces a dose dependent inhibition (up to 40$ at pCa 6), and this effect can be amplified by the phosphodiesterase inhibitor IBMX (3-isobutyl-1-methylxanthine) 10−4 M. The effect is similar in presence and absence of sodium fluoride 10 mM. Since in detergent treated skinned fibres the cell membrane and the sarcoplasmic reticulum are extracted and since the Ca2+ ion concentration was kept constant and buffered, we propose that c-AMP does not act via the cell membrane or the sarcoplasmic reticulum, but via phosphorylation of troponin I. The latter is the only component which becomes phosphorylated in skinned fibres during c-AMP induced relaxation, an effect which is also responsible for the inhibition of actomyosin ATPase at constant Ca2+ ion concentration (cf. Ray and England 1976).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00596172
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Skinned coronary smooth muscle: Calmodulin, calcium antagonists, and cAMP influence contractility (1983)
    Springer
    Basic research in cardiology 78 (1983), S. 462-471 
    Details
    ISSN: 1435-1803
    Keywords: coronary artery ; calcium ; calcium antagonists ; cyclic AMP ; skinned smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of Ca2+, calmodulin, cAMP, the catalytic subunit of cAMP-dependent protein kinase (CSU) and some Ca2+ antagonists were studied in chemically (Triton X-100) skinned coronary smooth muscle. Calmodulin increased the Ca2+ responsiveness of the muscle fiber as indicated by the reduction in the threshold as well as the half-maximal activating Ca2+ concentration. Trifluoroperazine, a calmodulin antagonist, inhibited Ca2+-calmodulin-induced contraction. Both cAMP anCSU were effective inhibitors of contraction induced at an intermediate Ca2+ concentration. Fendiline, a Ca2+-antagonist, at 2×10−4 M produced a significant inhibitory effect, which was reduced by increasing the Ca2+ concentration. From other Ca2+ antagonists tested, W-7, but not D600 and verapamil, produced some inhibitory effect. The data indicate that the responses of skinned coronary smooth muscle to Ca2+, calmodulin and cAMP are similar to those obtained with other skinned smooth muscles. Furthermore, skinned fiber preparation can serve as a useful tool to investigate possible direct effects of drugs on the activating and regulatory systems in smooth muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02070169
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    Paper (German National Licenses)
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