title: Relationships between the effects of superoxide anion and palmitoyl-L-carnitine on the Ca(2+)-ATPase of vascular smooth muscle sarcoplasmic reticulum.
abstract: In order to understand interactions between oxidants and non-antioxidants, relationships between the effects of superoxide anion radical (O2-) and palmitoyl-L-carnitine (PLC) on the Ca(2+)-ATPase of vascular smooth muscle sarcoplasmic reticulum were studied. PLC was ineffective in preventing the reduction of ferricytochrome c by O2-, suggesting that it has no O2(-)-scavenging properties. PLC exhibited a biphasic effect on Ca(2+)-ATPase activity, causing stimulation at low concentrations (3-10 microM) and inhibition at higher concentrations (30-1000 microM). The stimulatory effect on Ca(2+)-ATPase caused by 10 microM PLC was completely counteracted by O2-, whereas the stimulatory effect of L-cysteine (2 mM) was only diminished partially. Additive effects of PLC and L-cysteine attenuated the inhibitory effect of O2-, however, this appears to be due to L-cysteine alone. These results demonstrate that O2- can inhibit stimulatory effects of PLC on the Ca(2+)-ATPase, however, PLC does not block the inhibitory effect of O2-. Understanding interactions between oxidants/antioxidants and non-antioxidants at their cellular target proteins may provide essential information in the search for prevention of free radical injury.
authors.affiliation: Department of Physiology, Medical College of Virginia, Richmond 23298.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Suzuki
authors.forename: L
authors.initials: L
authors.lastname: Packer
authors.forename: G D
authors.initials: GD
authors.lastname: Ford
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000502:physiology; D002331:Carnitine / Q000494:pharmacology; D002417:Cattle; D003545:Cysteine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005609:Free Radicals; D019271:Hypoxanthine; D007042:Hypoxanthines / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000201:enzymology* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D010172:Palmitoylcarnitine / Q000494:pharmacology*; D012519:Sarcoplasmic Reticulum / Q000201:enzymology* / Q000648:ultrastructure; D013481:Superoxides / Q000494:pharmacology*; D014969:Xanthine Oxidase / Q000502:physiology
chemical_list: D000975:Antioxidants; D005609:Free Radicals; D007042:Hypoxanthines; D013481:Superoxides; D010172:Palmitoylcarnitine; D019271:Hypoxanthine; D014969:Xanthine Oxidase; D000252:Calcium-Transporting ATPases; D003545:Cysteine; D002331:Carnitine; D010100:Oxygen