Actions of arachidonic acid on erythrocyte membrane Rb permeability.
The effects of non-esterified arachidonic acid (AA) on erythrocyte membrane ion permeability have been studied using 86Rb flux measurements. [14C]AA was used to quantify membrane incorporation of AA and to show AA removal by albumin washing. The actions of vitamin E and other antioxidants on the effects of AA were examined. Reversible membrane incorporation of 700-2000 nmol AA per ml cells was achieved without significant haemolysis or morphological change. AA incorporation caused a reversible mean increase in bumetanide-sensitive Rb influx of 34% (S.E.M. 4.5, n = 23). This action could be partially prevented by co-incubation with vitamin E, but not by Trolox or dithioerythritol. AA incorporation caused an irreversible mean increase in residual Rb permeability (bumetanide and ouabain insensitive) of 130% (S.E.M. 22, n = 20), associated with a rise in intracellular Na and a fall in intracellular K concentrations. This action was also partially prevented by co-incubation with vitamin E. The effects of AA incorporation on Na,K-ATPase function were difficult to quantify because of the concomitant rises in intracellular Na but the data are consistent with approximately 20% inhibition of activity. Modulation of membrane ion permeability by AA appears to be partially mediated by lipid peroxidation and may have pathophysiological significance.
Dwight
J F
JF
Department of Medicine, King's College School of Medicine and Dentistry, London, UK.
Hendry
B M
BM
D016718:Arachidonic Acid / Q000494:pharmacology*; D002034:Bumetanide / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004226:Dithioerythritol / Q000494:pharmacology; D004232:Diuretics / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D005227:Fatty Acids / Q000097:blood; D006400:Hematocrit; D006801:Humans; D066298:In Vitro Techniques; D010042:Ouabain / Q000494:pharmacology; D012414:Rubidium Radioisotopes; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000097:blood; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D014810:Vitamin E / Q000494:pharmacology; D014882:Water-Electrolyte Balance / Q000187:drug effects
D004232:Diuretics; D004791:Enzyme Inhibitors; D005227:Fatty Acids; D012414:Rubidium Radioisotopes; D013439:Sulfhydryl Reagents; D002034:Bumetanide; D014810:Vitamin E; D016718:Arachidonic Acid; D010042:Ouabain; D004226:Dithioerythritol; D000254:Sodium-Potassium-Exchanging ATPase