Effect of Sodium on Potassium Fluxes at the Cell Membrane and Vacuole Membrane of Red Beet 1
AUTOR(ES)
Poole, Ronald J.
RESUMO
Slices of red beet (Beta vulgaris) washed for 5 to 6 days are known to accumulate Na+ in preference to K+ from solutions containing both ions. The present work, using ion concentrations of 1.0 mm or less, with Ca2+ added in some cases, shows that Na+ strongly inhibits K+ influx at the cell membrane (plasmalemma) while K+ efflux is increased to a lesser extent. This result from compartmental analysis is confirmed by short (15-minute) influx experiments, which indicate an immediate inhibitory effect of Na+ on K+ influx at the cell membrane. It is concluded that cation selectivity, even when Na+ is favored for uptake, is primarily determined at the cell membrane. Nevertheless, a high level of K+ in the cytoplasm is maintained during Na+ influx, by an inhibition of K+ transfer to the vacuole.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=396761Documentos Relacionados
- The dependence on external cation of sodium and potassium fluxes across the human red cell membrane at low temperatures.
- Carrier-mediated Potassium Efflux Across the Cell Membrane of Red Beet
- Microelectrode Measurements on Red Beet Vacuole 1: Biological Effect of Na+ OR NO3− Ions, Diffusing from the Microelectrode
- FACTORS WHICH MODIFY THE EFFECT OF SODIUM AND POTASSIUM ON BACTERIAL CELL MEMBRANES1
- POTASSIUM AND SODIUM OF RED BLOOD CELLS IN SICKLE CELL ANEMIA 1