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The Effects of Sodium and Potassium on Ouabain Binding by Human Erythrocytes
Ouabain binding by the human erythrocyte membrane is reversible, exhibits a high degree of chemical specificity, and can be detected at ouabain concentrations as low as 1 x 10(-10) M. The relation between ouabain binding and ouabain concentration can be described by a rectangular hyperbola permittin...
Autores principales: | , |
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Formato: | Texto |
Lenguaje: | English |
Publicado: |
The Rockefeller University Press
1972
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2226090/ https://www.ncbi.nlm.nih.gov/pubmed/4644328 |
Sumario: | Ouabain binding by the human erythrocyte membrane is reversible, exhibits a high degree of chemical specificity, and can be detected at ouabain concentrations as low as 1 x 10(-10) M. The relation between ouabain binding and ouabain concentration can be described by a rectangular hyperbola permitting determination of the maximal binding (B (max)) and the ouabain concentration at which ouabain binding is half-maximal (K(B)). Reducing the external sodium concentration increased K(B), while reducing the external potassium concentration decreased K(B). Neither cation altered B (max) The reciprocal of K(B) was a linear function of the sodium concentration at sodium concentrations ranging from 0 to 150 mM. Conversely, the relation between the reciprocal of K(B) and the external potassium concentration was nonlinear, and raising the potassium concentration above 4 mM produced no further increase in K(B). These results are compatible with a model which postulates that the erythrocyte membrane contains a finite number of receptors each composed of a glycoside-binding site and a cation-binding site. When sodium occupies the cation-binding site, the affinity of the glycoside site for ouabain is increased; when potassium occupies the cation-binding site the affinity of the glycoside site for ouabain is decreased. |
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