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  • 1
    Electronic Resource
    Electronic Resource
    Length dependence of calcium activated isometric force and immediate stiffness in living and glycerol extracted vascular smooth muscle (1982)
    Springer
    Pflügers Archiv 394 (1982), S. 174-181 
    Details
    ISSN: 1432-2013
    Keywords: Vascular smooth muscle ; Smooth muscle: mechanics ; Skinned fibres ; Stiffness ; Force-length relation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Vascular smooth muscle series elasticity was examined in living and glycerinated preparations as a function of the tissue length or calcium elicited force. Isometrically contracted smooth muscle strips were submitted to small quick stretches and releases (rise time 1.5 ms). The resulting immediate tension changes were proportional to the length changes for length steps ranging from −0.5% L0 to +2% L0. Plotting the immediate tension changes versus the length steps resulted in force-extension diagrams of the series elasticity (T1-curves). The linear parts of the T1-curves extrapolated to a common abscissa intercept of about −1% to −2% L0 irrespective of the tissue length or the degree of calcium activated force. The slopes of the T1-curves taken as the stiffness of the series elasticity increased in proportion to the isometric tension and depended on the tissue length or the degree of calcium activation in a similar way as tension. It is concluded that tension changes due to changes in the calcium concentration or the tissue length are caused by a change in the number of attached crossbridges. Results obtained in “skinned” fibres were similar to the one obtained in living fibres indicating that electromechanical coupling was not a major factor in determining the decrease in isometric tension and stiffness at short lengths.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00582921
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Relaxation of skinned coronary arteries depends on the relative concentrations of Ca2+, calmodulin and active cAMP-dependent protein kinase (1985)
    Springer
    Pflügers Archiv 405 (1985), S. 70-76 
    Details
    ISSN: 1432-2013
    Keywords: Skinned coronary arteries ; Smooth muscle ; Regulation of contractile tone ; cAMP-dependent protein kinase ; cAMP-dependent modulation of contractile tone ; Calmodulin ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Maximally contracted detergent skinned coronary smooth muscle fibres are relaxed by lowering the concentration of free Ca2+. The extent and rate of relaxation depends on the concentration of free Ca2+ and calmodulin (CaM) suggesting that it is the Ca2+. CaM complex which is responsible for maintaining tension. At a fixed concentration of Ca2+ and CaM further relaxation can be achieved by addition of the catalytic subunit of the cAMP-dependent protein kinase (cAMP-kinase). The extent as well as the relaxation rate depend on the concentration of cAMP-kinase (0.01–0.5 μM) and both are antagonized by high concentrations of Ca2+ and CaM. The Ca2+-requirement for obtaining half maximal concentration is shifted from 1.1 μM to 6.3 μM Ca2+ in the presence of 0.5 μM cAMP-kinase. These data indicate that the response of the contractile apparatus to a change in the free [Ca2+] can be modulated by cAMP-kinase at the level of the contractile proteins. It is further suggested that the tone of coronary smooth muscle is determined by the relative and not by the absolute concentrations of Ca2+, CaM and cAMP-kinase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00591100
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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