The high-frequency (HF) electron current induced in a de discharge plasma by superimposing a HF electric field presents a useful tool for the diagnostics of the time-dependent electron behavior of the plasma. This response to the HF field has been recently studied in diffusive discharge plasmas at lower gas pressures and discharge currents. These studies are extended to medium-pressure plasmas operating in the diffusive as well as in the constricted mode. In particular, the impact of the electron-electron interaction on the phase delay between the-HF field and electron current in constricted column plasmas has been experimentally and theoretically analyzed. Furthermore, the problem has been studied if; under the conditions of pronounced electron-electron interaction, the determination of the electron density will further on be possible by using the phase delay. The measurements of the delay have been performed by means of the microwave resonator method in a medium-pressure krypton glow discharge operating in the diffusive as well as the strongly constricted mode. In addition, the delay has been theoretically determined by treating the appropriate time-dependent electron kinetic equation at high frequencies of the superimposed microwave field.