title: Peroxide inactivates calcium pumps in pig coronary artery.
abstract: To study the effects of hydrogen peroxide, pig coronary artery smooth muscle subcellular fractions enriched in plasma membrane (F2) or sarcoplasmic reticulum (F3) were incubated in various concentrations of peroxide and 5 mM azide. ATP-dependent azide-insensitive oxalate-stimulated Ca2+ uptake was determined for F3 and phosphate-stimulated uptake for F2. Only 1.5-5 microM hydrogen peroxide was required for 50% inhibition of the Ca2+ uptake by F3, but the corresponding concentration for F2 was 10-50 microM. This effect was not prevented by superoxide dismutase. Hydrogen peroxide inhibited the Ca(2+)-dependent formation of a 115-kDa acylphosphate band in F3 and 140- and 115-kDa bands in F2. The inhibition of Ca2+ uptake in F3, however, exceeded the inhibition of the acylphosphate formation. Efflux of Ca2+ from F2 and F3 was enhanced by hydrogen peroxide but F3 was more sensitive than F2. We conclude that hydrogen peroxide has dual effect on Ca2+ dynamics in the coronary artery smooth muscle, i.e., it inactivates the Ca2+ pumps and increases membrane permeability to Ca2+. The effect is more pronounced on sarcoplasmic reticulum than on plasma membrane. Intrinsic catalase may, however, provide partial protection against such damage.
authors.affiliation: Department of Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
authors.forename: A K
authors.initials: AK
authors.lastname: Grover
authors.forename: S E
authors.initials: SE
authors.lastname: Samson
authors.forename: V P
authors.initials: VP
authors.lastname: Fomin
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects; D003331:Coronary Vessels / Q000187:drug effects*; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D066298:In Vitro Techniques; D010710:Phosphates / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013552:Swine
chemical_list: D010710:Phosphates; D006861:Hydrogen Peroxide; D000252:Calcium-Transporting ATPases; D002118:Calcium