title: Alterations in cardiac membrane Ca2+ transport during oxidative stress.
abstract: Although cardiac dysfunction due to ischemia-reperfusion injury is considered to involve oxygen free radicals, the exact manner by which this oxidative stress affects the myocardium is not clear. As the occurrence of intracellular Ca2+ overload has been shown to play a critical role in the genesis of cellular damage due to ischemia-reperfusion, this study was undertaken to examine whether oxygen free radicals are involved in altering the sarcolemmal Ca2(+)-transport activities due to reperfusion injury. When isolated rat hearts were made globally ischemic for 30 min and then reperfused for 5 min, the Ca2(+)-pump and Na(+)-Ca2+ exchange activities were depressed in the purified sarcolemmal fraction; these alterations were prevented when a free radical scavenger enzymes (superoxide dismutase plus catalase) were added to the reperfusion medium. Both the Ca2(+)-pump and Na(+)-Ca2+ exchange activities in control heart sarcolemmal preparations were depressed by activated oxygen-generating systems containing xanthine plus xanthine oxidase and H2O2; these changes were prevented by the inclusion of superoxide dismutase and catalase in the incubation medium. These results support the view that oxidative stress during ischemia-reperfusion may contribute towards the occurrence of intracellular Ca2+ overload and subsequent cell damage by depressing the sarcolemmal mechanisms governing the efflux of Ca2+ from the cardiac cell.
authors.affiliation: Division of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, Winnipeg, Manitoba, Canada.
authors.forename: I M
authors.initials: IM
authors.lastname: Dixon
authors.forename: M
authors.initials: M
authors.lastname: Kaneko
authors.forename: T
authors.initials: T
authors.lastname: Hata
authors.forename: V
authors.initials: V
authors.lastname: Panagia
authors.forename: N S
authors.initials: NS
authors.lastname: Dhalla
mesh_terms: D000818:Animals; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism; D005609:Free Radicals; D006861:Hydrogen Peroxide / Q000378:metabolism; D006878:Hydroxides / Q000378:metabolism; D017665:Hydroxyl Radical; D007700:Kinetics; D008297:Male; D015428:Myocardial Reperfusion Injury / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012508:Sarcolemma / Q000378:metabolism*; D012964:Sodium / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D005609:Free Radicals; D006878:Hydroxides; D013481:Superoxides; D017665:Hydroxyl Radical; D012964:Sodium; D006861:Hydrogen Peroxide; D000252:Calcium-Transporting ATPases; D010100:Oxygen; D002118:Calcium