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  • 1
    Electronic Resource
    Electronic Resource
    A biphasic change in contractile proteins during the development of cardiac hypertrophy in pigs (1987)
    Springer
    Basic research in cardiology 82 (1987), S. 1-8 
    Details
    ISSN: 1435-1803
    Keywords: cardiac hypertrophy ; myosin ATPase ; actin-activated myosin ATPase ; myofibrillar ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A non-failing hypertrophy of the left ventricle was produced in the pig heart by supravalvular banding of aorta for 4, 8 and 12 weeks and the myosin and myofibrillar adenosine triphosphatase activities were measured. A significant increase in myosin Ca2+-ATPase activity was seen at 4 weeks of hypertrophy, but at 8 and 12 weeks this activity was significantly decreased compared to sham control. Similar changes were also seen in actin-activated myosin ATPase activities at 4, 8 and 12 weeks of hypertrophy. There were no changes in the K+- and NH4 +-EDTA-stimulated ATPase activities of myosin. Basal ATPase activities of myofibrils were decreased at 4 and 8 weeks of hypertrophy and there was no change in this activity at 12 weeks of hypertrophy. Ca2+ stimulated ATPase activity of myofibrils was significantly increased at 4 weeks, normal at 8 weeks and significantly reduced at 12 weeks of hypertrophy. The changes in ATPase activities were not due to any alterations of proteins by high concentrations of salts during the purification of myosin. The non-hypertrophied right ventricle from the banded animals did not show any change in the basal or Ca2+ stimulated myofibrillar ATPase activities. It is suggested that hypertrophy of the myocardium is accompanied by specific changes in the enzyme activities of the contractile proteins and the biphasic responses may correlate with the functional state of the myocardium subjected to a chronic increase in pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01907047
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Alterations in heart sarcolemmal Ca2+-ATPase and Ca2+-binding activities due to oxygen free radicals (1990)
    Springer
    Basic research in cardiology 85 (1990), S. 45-54 
    Details
    ISSN: 1435-1803
    Keywords: freeradicals ; hydrogen peroxide ; Ca2+-ATPase ; Ca2+-binding ; heart sarcolemma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Effects of oxygen free radicals on Ca2+/Mg2+ ATPase and ATP-independent Ca2+-binding activities were examined in rat heart sarcolemma. Membranes were incubated with different oxygen radical generating media such as xanthine + xanthine oxidase, hydrogen peroxide, and hydrogen peroxide + Fe2+. In the presence of xanthine + xanthine oxidase, Ca2+ ATPase activity was stimulated and this effect was prevented by the addition of superoxide dismutase. Hydrogen peroxide also showed a significant increase in Ca2+-ATPase activity in a dose-dependent manner and this effect was blocked by catalase. On the other hand, a combination of hydrogen peroxide + Fe2+ decreased Ca2+-ATPase activity; this depression was prevented by the addition of D-mannitol. The observed change in Ca2+-ATPase activity due to oxygen free radicals was associated with changes in Vmax, whereas Ka remained unaffected. Both xanthine + xanthine oxidase and hydrogen peroxide increased whereas, hydrogen peroxide + Fe2+ inhibited the ATP-independent Ca2+-binding activities. It is suggested that oxygen free radicals may influence Ca2+ movements in the cell by altering the Ca2+/Mg2+ ATPase and Ca2+-binding activities of the membrane and these effects may be oxygen-radical species specific.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01907013
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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