Liquid crystal microdisplays are heavily used in applications ranging from static and quasi-static images to video-rate displays. Antiferroelectric liquid crystals with asymmetric response exhibit good properties to be employed in this kind of devices, for example in mobile telephones. Asymmetric response arises from dissimilar surface conditioning onto the cell glass plates. The resulting asymmetric antiferroelectric devices feature multiplexed analogue grey scales with very simple driving schemes. In this work, a comparative study of properties of antiferroelectric liquid crystal cells with symmetric and asymmetric response is carried out. Asymmetric cells give rise dissimilar current peaks depending on the polarity of the applied waveform. This effect may stem from various contributions, such as ionic conductance and free charges accumulated superimposed to the symmetric antiferroelectric response.