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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Stiffness and tension during and after sudden length changes of glycerinated rabbit psoas muscle fibres (1978)
    Springer
    European biophysics journal 4 (1978), S. 223-236 
    Details
    ISSN: 1432-1017
    Keywords: Actin-myosin interactions ; Muscle mechanics ; ATP hydrolysis in skeletal muscle ; Rigor state of muscle ; Cross-bridge slippage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract A sudden stretch (within 0.3 ms) of glycerol-extracted rabbit psoas fibre bundle suspended in ATP-salt solution caused an immediate tension increase followed by a rapid tension decay (quick phase) which was nearly completed within 3 ms. The quick phase was missing or much reduced in the absence of ATP when the fibres were in rigor. Since the immediate stiffness of the fibres was nearly the same at the onset and at the end of the quick phase, the latter cannot be due to cross-bridges detachment per se. However, it may be ascribed to a conformational change (e.g. rotation) of attached bridges as suggested by Huxley and Simmons. Alternatively it might be explained by a slippage of attached cross-bridges. This mechanism would presuppose fast detachment and reattachment of strongly strained cross-bridges during the quick phase. Evidence for such a process was obtained by analysing the tension transients obtained when fibre bundles subjected to a large stretch were subsequently (within 10 ms) released to the initial length, as well as from stiffness measurements during the sudden length change: The stiffness was not found to be constant either during stretch or during the release. This may be taken to mean that the number of attached cross-bridges does not remain constant even during a rapid length change. In view of these results, the model proposed by Huxley and Simmons might be extended to take account of rapid attachment and detachment of crossbridges.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426087
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  • 3
    Electronic Resource
    Electronic Resource
    Polarization of tryptophan fluorescence measurements in muscle (1980)
    Springer
    European biophysics journal 6 (1980), S. 81-93 
    Details
    ISSN: 1432-1017
    Keywords: Myosin cross bridge orientation ; Tryptophan fluorescence ; Actinmyosin interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The degree of polarization of the intrinsic tryptophan fluorescence of glycerinated single muscle fibres or fibre bundles (rabbit psoas or dorsal longitudinal muscle of Lethocerus maximus) was measured: a) With sufficiently high (15 mM) ATP concentration or when an ATP regenerating system was used no difference in the degree of polarization of a contracting and a relaxed muscle was detected, whereas a distinct difference was detected between the relaxed and the rigor state. In contrast a distinct difference between the relaxed and contracting state was obtained at low ATP concentrations (5 mM). This difference is interpreted to be caused by an ATP-free core (rigor core) in the centre of the fibre. b) No change in the polarization degree was detected after a rapid release of the contracting muscle. c) In rigor state no difference in the degree of polarization of the tryptophan fluorescence was observed in the presence or absence of AMPPNP (concentration 0.5 mM). These findings and the lack of difference between the polarization degree of the contracting and the relaxed muscle is interpreted to indicate that the polarization degree of the tryptophan fluorescence is not sensitive to the orientation of the cross bridges, or that the cross bridges do not rotate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00535746
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  • 4
    Electronic Resource
    Electronic Resource
    Stiffness and tension during and after sudden length changes of glycerinated single insect fibrillar muscle fibres (1979)
    Springer
    European biophysics journal 5 (1979), S. 255-276 
    Details
    ISSN: 1432-1017
    Keywords: Actomyosin interaction ; Muscle mechanics ; Cross bridge slip-page ; Contraction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Rapid length changes were applied (within 0.2 ms or 0.4 ms) to single isometrically contracted glycerol extracted muscle fibres of the dorsal longitudinal muscle ofLethocerus maximus suspended in an Ca2+ and ATP containing solution at 20–23
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02426662
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  • 5
    Electronic Resource
    Electronic Resource
    Investigation of the temperature dependence of the cross bridge parameters for attachment, force generation and detachment as deduced from mechano-chemical studies in glycerinated single fibres from the dorsal longitudinal muscle of Lethocerus maximus (1979)
    Springer
    European biophysics journal 6 (1979), S. 1-29 
    Details
    ISSN: 1432-1017
    Keywords: Myofibrillar ATPase ; Mechano-chemistry of muscle ; Insect fibrillar muscle ; Muscular energetics ; Kinetics of actin-myosin interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract 1) A study is presented on the effect of temperature on the mechanochemical states involved in the cross bridge cycle of single glycerinated dorsal longitudinal fibres from Lethocerus. Contraction was induced by immersing the fibre in a MgATP-salt solution at Ca2+∼10 ΜM (pH 6.7). 2) Rising the temperature increases the rates of isometric tension generation following an increase in the [Ca2+] from 0.01 to 10 ΜM as well as the steady state levels of isometric tension and the rates of ATP splitting. 3) Tension transients following stretches of rise times 250 Μs and amplitudes up to 0.4% L i comprise at least four phases: an elastic phase the amplitude of which decreases by raising the temperature; a biphasic quick phase of tension decay with a mean Q 10=2; a delayed tension rise (Q 10∼5). 4) Tension transients following releases of fall time 250 Μs and amplitudes up to 0.3% L i also comprise four phases: an elastic phase comparable to that observed following stretches; a deactivation phase composed of a single exponential and a slow recovery phase. 5) The number of cross bridges attached to the actin at any moment is not changed during the elastic and quick recovery phase following a release as well as during the elastic and fast quick phase following a stretch. However, the number of attached cross bridges decreases during the deactivation phase. 6) The early phases of tension adjustment (T curves) which were recorded during the releases showed a marked dependence on temperature. The T curves fitted with high accuracy the Huxley and Simmons (1971) predictions of cross bridge rotation. 7) Analysis of the T curves in terms of the Huxley and Simmons (1971) model shows that a) the stiffness of a single cross bridge (D=1.2 104− N/m) obeys Hook's law; b) the number of myosin heads attached to actin (24% of the total number) is not altered during releases; c) rotation of myosin heads from a perpendicular to an acute angled position extends the elastic element of a cross bridge by 11 nm; d) at 25
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00537592
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  • 6
    Electronic Resource
    Electronic Resource
    Cross bridge slippage in skinned frog muscle fibres (1980)
    Springer
    European biophysics journal 7 (1980), S. 107-124 
    Details
    ISSN: 1432-1017
    Keywords: Actomyosin interaction ; Muscle mechanics ; Cross bridge slippage ; Contraction mechanism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Mechanically skinned single fibres of the semitendinosus muscles of Rana esculenta were investigated at ca. 4
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00538402
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  • 7
    Electronic Resource
    Electronic Resource
    Length dependent state of activation — Length change dependent kinetics of cross bridges in skinned insect flight muscle (1981)
    Springer
    European biophysics journal 7 (1981), S. 139-169 
    Details
    ISSN: 1432-1017
    Keywords: Insect-fibrillar muscle ; Cross bridge kinetics ; Actin-Myosin interaction ; Length dependent activation of muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Stretch induced activation and release induced deactivation of single glycerol-extracted insect flight muscle fibres were investigated. The results are interpreted to indicate that the muscle length controls the number of acting cross bridges, whereas their attachment-detachment kinetics in mainly determined by the state of strain of the cross bridges. It is concluded that the net detachment rate of the cross bridges is enhanced if the muscle is released thereby “unloading” the cross bridges. This behaviour of the unloaded cross bridge is a basic postulation of most of the molecular muscle contraction models. 1. The delayed tension rise induced by stretches of different amplitudes could be restored to the level before the stretch by a release to the initial length. 2. The delayed tension decrease induced by a release of moderate (up to δL=1.5% L i)amplitude is quantitatively restored within the delayed increase induced by the restretch to the initial length. 3. Stiffness, which decreased during the delayed tension drop after release, is restored during a delayed stiffness increase effected by a restretch to the initial length. 4. The rate and the extent of the stiffness drop after release increased with increasing amplitude of the release and with increasing temperature. 5. After the deactivation, i.e., after tension and stiffness achieved a new steady level after the release, the attached cross bridges are already in the same state of strain as they were before the release. This finding is interpreted to indicate that within the deactivation phase all cross bridges attached prior the release are replaced by cross bridges attached after the release. 6. The rate of tension and stiffness decay after release does not depend on the absolute muscle length but on the amplitude of the release which induced the deactivation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00539176
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  • 8
    Electronic Resource
    Electronic Resource
    The determination of ionospheric plasma drifts by a rocket-borne electrostatic flux meter
    Amsterdam : Elsevier
    Planetary and Space Science 22 (1974), S. 1131-1138 
    Details
    ISSN: 0032-0633
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0032-0633(74)90067-1
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  • 9
    Electronic Resource
    Electronic Resource
    Low Ca 2+ impedes cross-bridge detachment in chemically skinned Taenia coli (1982)
    [s.l.] : Nature Publishing Group
    Nature 300 (1982), S. 775-776 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The Ca2+-jump technique4 allows the Ca2+ concentration to be changed in small bundles of chemically skinned muscle fibres within fractions of a second. Compared with this time scale, the mechanical response in chemically skinned T. coli is much slower; the broken line marked ±Ca2+ in Fig. 1 ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/300775a0
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  • 10
    Electronic Resource
    Electronic Resource
    Skinned smooth muscle: Time course of force and ATPase activity during contraction cycle (1984)
    Springer
    Cellular and molecular life sciences 40 (1984), S. 174-176 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The time course of ATPase activity and force has been determined during contraction and relaxation in skinned (hyperpermeable) anterior byssus retractor muscle, ABRM, ofMytilus edulis and compared with corresponding measurements on skinned taenia coli of guinea-pigs. Following a calcium-induced contraction, lowering the [Ca++] to 10−8 M rapidly reduces ATPase activity within 2 min to resting levels while force declines only to about 30–50% of maximal tension within the same time. Thus slow relaxation is due to a ‘catch-like-state’ which is common to different kinds of smooth muscles and can be reduced with cAMP in ABRM and by Pi in taenia coli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01963585
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