Changes of intracellular Na(+) concentration in erythrocytes caused by pulsed electrical field

Changes of sodium ionic concentration of human erythrocytes applied to pulsed electrical field (PEF) were studied by using shift reagent and NMR spectroscopy. The results show that the concentration of intraceUular Na(+) increases with the increasing intensity of PEF when the erythrocytes are applied to PEF with higher intensities. The relationship between intracellular Na(+) concentrations and the intensities of PEF does not follow linear or exponential behavior. As the intensities increase, the intracellular Na(+) concentrations increase even faster by an exponential curve. However under effects of PEF at lower intensities, intracellular Na(+) concentration decreases. Ouabain can inhibit the decrease of intracellular Na(+) concentration, and the inhibition increases with the increasing concentration of ouabain, suggesting that Na(+), K(+)-ATPase on cell membrane can be activated by PEF at lower intensities. Direct measurement of activities of the enzyme by using Malachite green method has confirmed this observation. Cell permeabilities to ions, activation of enzymes by electrical fields and transmission of physical signals like PEF across cell membranes are discussed.