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  • 1
    Electronic Resource
    Electronic Resource
    Contractile properties of skinned preparations from ischaemic canine myocardium and coronary arteries (1993)
    Springer
    Pflügers Archiv 425 (1993), S. 82-89 
    Details
    ISSN: 1432-2013
    Keywords: Myocardial ischaemia ; Myocardium ; Vascular smooth muscle ; Dog ; Contractile proteins ; Calcium dependence ; Myosin phosphorylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The influence of prolonged ischaemia on the regulation of contraction in the myocardium and in the smooth muscle of coronary arteries was investigated. Chemically skinned preparations were used which enabled the contraction to be studied with the environment of the contractile filaments controlled. Myocardial ischaemia was produced in anaesthetized adult beagle dogs by occlusion of the left anterior descending artery for 3 h and followed by 30 min reperfusion. Myocardial tissue and segments from coronary arteries were obtained from the ischaemic infarcted wall region (“in vivo ischaemic”) and compared with control preparations from perfused coronary arteries and from the free wall of the left ventricle. Coronary and myocardial preparations were also obtained from the heart after a 3 h period in vitro under anoxic conditions at 37°C (“in vitro ischaemic”) simulating a state of extreme ischaemia. Control myocardial fibres were fully relaxed at pCa (-log-[Ca2+]) 9 and developed 24±5% (n=7) of maximum force at intermediate calcium concentration (pCa 5.5). In contrast, the in vivo and in vitro ischaemic preparations produced force at pCa 9 (28±13 and 39±8%, respectively, n=5 and 7) and showed an increased force development at pCa 5.5 (53±11 and 75±5%). The in vivo and in vitro ischaemic coronary arteries relaxed more slowly following calcium removal than control vessels. The in vitro ischaemic vascular preparations developed active force at pCa 9 and showed increased levels of myosin light chain phosphorylation and reduced phosphatase activity. This suggests a reduced rate of dephosphorylation as a cause for the changes in contracile behaviour of the smooth muscle. In conclusion, extreme ischaemia in vitro is associated with a loss of calcium regulation and an increased calcium sensitivity of the contractile system in myocardium and changes in the phosphorylation/dephosphorylation reactions of coronary arteries. The changes in myocardium appear to occur also during ischaemia in vivo, and might contribute to contracture development in cells under conditions when adenosine triphosphate synthesis is reestablished after reperfusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00374507
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Lactate dehydrogenase activity and isoform distribution in normal and hypertrophic smooth muscle tissue from the rat (1991)
    Springer
    Pflügers Archiv 419 (1991), S. 230-234 
    Details
    ISSN: 1432-2013
    Keywords: Smooth muscle ; Lactate dehydrohgenase ; Isoforms ; Hypertrophy, Rat urinary bladder ; Rat portal vein ; Rat arota
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The lactate dehydrogenase (LDH) activity and isoform distribution of LDH were investigated in tissue samples from the rat portal vein, aorta and urinary bladder. In addition, samples were obtained from hypertrophic urinary bladder. The total LDH activity per unit smooth muscle volume was higher in the urinary bladder compared to that in portal vein and aorta. Five LDH isoforms, reflecting different combinations of the two polypeptide chains denoted H and M, could be separated by agarose gel electrophoresis. The aorta contained more of the H form compared to the portal vein and urinary bladder. This difference suggests that the aorta, which is a slow smooth muscle, is more adapted for aerobic metabolism than the faster muscles of portal vein and urinary bladder. In the hypertrophic urinary bladder a shift in LDH isoform pattern towards less of the H form was found, which correlates with a better maintenance of contraction in anoxia in this type of hypertrophic smooth muscle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00371100
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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