[An ionometric study of Na+ and K+ fluxes across the nystatin-modified human erythrocyte membrane].

The application of ion-selective electrodes is discussed for the kinetic determination of K+ and Na+ concentrations in the system, containing human red blood cells modified by nystatin. A series of mixed solutions was worked out, according to which the Na(+)-glass and the K(+)-thick membrane valinomycin electrodes were calibrated. The human erythrocytes were washed for 3 times with the basic solution (in mol per liter: 0.141 NaCl, 0.004 KCl, 0.002 CaCl2, 0.003 MgCl2, 0.01 glucose), and then were resuspended in it. The suspension was kept in a shaking bath at 37 degrees C. The modification of the cell membranes was performed by the introduction of different amounts of the antibiotic nystatin into the probe. Under these conditions the concentration of Na+ decreased, while K+ concentration increased. The values of concentration were registered ionometrically. In an hour and a half the stationary lines were obtained. Being based on the values of the stationary cation concentrations and the final concentrations, registered after the complete lysis of erythrocytes promoted by saponin, the ratio of cation fluxes across the modified membrane to the flux across the nonmodified membrane was calculated in accordance with the Hodgkin-Katz equation.