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The ATP dependence of a ouabain-sensitive sodium efflux activated by external sodium potassium and lithium in human red cells

1976; Elsevier BV; Volume: 433; Issue: 3 Linguagem: Inglês

10.1016/0005-2736(76)90280-7

1879-2642

Luis Beaugé, Elena del Campillo,

Neonatal Health and Biochemistry

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+.