title: The ATP dependence of a ouabain-sensitive sodium efflux activated by external sodium, potassium and lithium in human red cells.
abstract: The stimulation of ouabain-sensitive Na+ efflux by external Na+, K+ and Li+ was studied in control and ATP-depleted human red cells. In the presence of 5 mM Na+, with control and depleted cells, Li+ stimulated with a lower apparent affinity than K+, and gave a smaller maximal activation than K+. The ability of Na+, K+ and Li+ to activate Na+ efflux was a function of the ATP content of the cells. Relative to K+ both Na+ and Li+ became more effective activators when the ATP was reduced to about one tenth of the control values. At this low ATP concentration Na+ was absolutely more effective than K+.
mesh_terms: D000255:Adenosine Triphosphate / Q000097:blood / Q000494:pharmacology*; D001665:Binding Sites; D001693:Biological Transport, Active; D002794:Choline / Q000494:pharmacology; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008094:Lithium / Q000494:pharmacology*; D010042:Ouabain / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology*; D012964:Sodium / Q000097:blood* / Q000494:pharmacology
chemical_list: D010042:Ouabain; D000255:Adenosine Triphosphate; D008094:Lithium; D012964:Sodium; D002794:Choline; D011188:Potassium