Lipid peroxidation both inhibits Ca(2+)-ATPase and increases Ca2+ permeability of endoplasmic reticulum membrane.
Incubation of reticular membranes with Fe(2+)-EDTA and H2O2 plus Fe(2+)-EDTA at 37 degrees C for 30 min led to the loss of membrane's efficiency to sequester Ca2+ to 21.8% and 3.6% of control values, respectively. The incubation of microsomes with Fe(2+)-EDTA and H2O2 plus Fe(2+)-EDTA also caused decrease of Ca(2+)-ATPase activity; to 44.9% and 44.4% (measured under the same conditions as Ca(2+)-uptake) or to 79.6% and 62.1% (uncoupled from Ca2+ transport by detergent). In addition, incubation of membranes with Fe(2+)-EDTA and H2O2 plus Fe(2+)-EDTA at 37 degrees C for 30 min led to the increase of Ca2+ permeability to 125.1% and 124.2%, respectively. Preincubation of membranes with membrane-soluble antioxidants (U-74500A, U-83836E, t-butyl hydroxytoluene and stobadine) protected the reticular membranes against depression of Ca2+ uptake values and Ca(2+)-ATPase inhibition in a dose and an antioxidant nature dependent manner. Our results indicate that both processes, Ca(2+)-ATPase inhibition and increase of endoplasmic reticulum membrane Ca2+ permeability, participate in the lipid peroxidation induced loss of membrane's efficiency to sequester Ca2+.
Racay
P
P
Comenius University, Jessenius Faculty of Medicine, Department of Medical Biochemistry, Martin, Slovak Republic.
Kaplán
P
P
Mézesová
V
V
Lehotský
J
J
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D001921:Brain / Q000378:metabolism; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D002243:Carbolines / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000502:physiology*; D002839:Chromans / Q000494:pharmacology; D004492:Edetic Acid / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005296:Ferrous Compounds / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015227:Lipid Peroxidation / Q000502:physiology*; D008861:Microsomes / Q000378:metabolism; D010879:Piperazines / Q000494:pharmacology; D011281:Pregnatrienes / Q000494:pharmacology; D011817:Rabbits
D000975:Antioxidants; D002243:Carbolines; D002839:Chromans; D005296:Ferrous Compounds; D010879:Piperazines; D011281:Pregnatrienes; C066382:U 78517F; D002084:Butylated Hydroxytoluene; D004492:Edetic Acid; D006861:Hydrogen Peroxide; D000252:Calcium-Transporting ATPases; C053356:U 74500A; D002118:Calcium; C100106:dicarbine