title: Effect of some antioxidants on sarcoplasmic reticulum Ca2+-ATPase activity from rabbit skeletal muscle.
abstract: OBJECTIVE
  Effects of phenolic antioxidants, synthetized (trolox, pyridoindole stobadine) and plant extracts (EGb 761 and Pycnogenol) were investigated on the activity of Ca(2+)-ATPase from sarcoplasmic reticulum (SR) of rabbit skeletal muscle to examine their potency to modulate the activity of this calcium level regulating enzyme.
  
  
  METHODS
  SR vesicles and pure Ca(2+)-ATPase were isolated by ultracentrifugation. Ca(2+)-ATPase activity was measured spectrophotometrically by enzyme-coupled assay.
  
  
  RESULTS
  Pycnogenol (Pyc) significantly decreased the activity of Ca(2+)-ATPase incorporated into SR vesicles as well as the activity of purified Ca(2+)-ATPase, the latter with respect to both enzyme substrates, Ca(2+) and ATP. Trolox, stobadine and EGb 761 did not influence significantly the activity SR- vesicle incorporated or pure Ca(2+)-ATPase, the latter with respect to either substrate, in spite of alterations of kinetic parameters in some cases.
  
  
  CONCLUSIONS
  The decrease of SR Ca(2+)-ATPase activity induced by Pyc may be associated with its proapoptotic and anticancerogenic properties.
authors.affiliation: Institute of Experimental Pharmacology, Slovak Academy of Sciences, Bratislava, Slovakia. exfamima@savba.sk
authors.forename: Miriam
authors.initials: M
authors.lastname: Strosová
authors.forename: Janka
authors.initials: J
authors.lastname: Karlovská
authors.forename: Pavol
authors.initials: P
authors.lastname: Galbavý
authors.forename: L'ubica
authors.initials: L
authors.lastname: Horáková
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000201:enzymology*; D010936:Plant Extracts; D011817:Rabbits; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D005419:Flavonoids; D010936:Plant Extracts; C024070:pycnogenols; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D002118:Calcium