Membrane ion transport systems during oxidative stress in rodent brain: protective effect of stobadine and other antioxidants.
The effect of oxidative stress in vitro induced by radical generating systems (RGS) (Fe2+-EDTA and Fe2+-EDTA plus H2O2) on synaptosomal and microsomal ion transport systems as well as on the membrane fluidity was investigated. Oxidative insult reduced Na+, K+-ATPase activity by 50.7% and Na+-dependent Ca2+ uptake measured in choline media by 46.7%. Membrane fluidity was also significantly reduced as observed with the fluorescent probe. Stobadine (ST) prevented the decrease in membrane fluidity and Na+-dependent Ca2+ uptake, however Na+, K+-ATPase activity was only partially protected, indicating a more complex mechanism of inhibition. Incubation of microsomes with RGS led to the loss of ability of membranes to sequester Ca2+, as well as to the decrease of Ca2+-ATPase activity and to the increase of Ca2+ permeability to 125.1%. The relative potency of the two RGS to decrease membrane fluidity correlated well with the system's potencies to induce lipid peroxidation. The extent of protection against depression of Ca2+ uptake values and Ca2+-ATPase activity by membrane soluble antioxidants (U-74500A, U-83836E, t-butylated hydroxytoluene-BHT and ST) was dependent on the experimental conditions and on the dose and nature of antioxidant used. ST seems to be at least as affective as BHT and 21-aminosteroids, and more potent than tocopherol acetate. Water soluble glutathione had no significant effect on the RGS induced inhibition of Ca2+-ATPase activity. Combination of ST with glutathione enhanced ST antioxidant efficacy, so drug combination might be beneficial therapeutically.
Lehotský
J
J
Comenius University, Jessenius Medical Faculty, Martin, Slovakia.
Kaplán
P
P
Racay
P
P
Matejovicová
M
M
Drgová
A
A
Mézesová
V
V
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001693:Biological Transport, Active / Q000187:drug effects; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002243:Carbolines / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D005849:Gerbillinae; D066298:In Vitro Techniques; D015227:Lipid Peroxidation / Q000187:drug effects; D008560:Membrane Fluidity / Q000187:drug effects; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D016548:Prosencephalon / Q000378:metabolism / Q000648:ultrastructure; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D012154:Reticular Formation / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D019831:Sodium-Calcium Exchanger / Q000037:antagonists & inhibitors / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013574:Synaptosomes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
D000975:Antioxidants; D002243:Carbolines; D018696:Neuroprotective Agents; D017382:Reactive Oxygen Species; D019831:Sodium-Calcium Exchanger; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium; C100106:dicarbine