title: Stimulation of monovalent cation fluxes by electron donors in the human red cell membrane.
abstract: When human red cells are incubated at 37 degrees C with the artificial electron donor system ascorbate + phenazine methosulphate the fluxes of Rb+ (K+) through the cell membrane are increased. The effect of this donor system is much stronger in energy-depleted than in normal cells. The same effects are produced by HS-glutathione, NADH or NADPH loaded into resealed ghosts, but these electron donors were ineffective when added to the incubation medium. The Rb+ (K+) fluxes induced by electron donors resemble closely those induced by an increase of intracellular Ca2+ (Gardos effect). The electron donors require the presence of intracellular Ca2+ to be effective, but at levels that do not stimulate by themselves the fluxes of K+. Flavoenzyme inhibitors (atebrin and chlorpromazine), oligomycin and quinine prevented the effects of both electron donors and Ca2+ alone; antimycin, upcouplers and ethacrynic acid inhibited them partially; ouabain, furosemide, and rotenone had no effect. The results could be explained if the effect of electron donors is to bring about a change in the redox state of some membrane component(s) that makes intracellular Ca2+ more effective to elicit rapid K+ movements. Plasma membrane oxidoreductase activities could be engaged in this change.
mesh_terms: D001205:Ascorbic Acid / Q000494:pharmacology; D001693:Biological Transport, Active / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D004579:Electron Transport; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D008773:Methylphenazonium Methosulfate / Q000494:pharmacology; D011188:Potassium / Q000097:blood*; D012413:Rubidium / Q000097:blood; D012964:Sodium / Q000097:blood*
chemical_list: D007473:Ion Channels; D008773:Methylphenazonium Methosulfate; D012964:Sodium; D012413:Rubidium; D001205:Ascorbic Acid; D011188:Potassium; D002118:Calcium