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
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