Using the general current-conserving theory developed by Buttiker for ac transport, the dynamical conductance of InAs/GaSb/InAs and InAs/AlSb/GaSb/AlSb/InAs structures are calculated within the two-band k⋅p model. In these interband systems, there is an energy window ∆E within which the transmission coefficient is nonzero. When the frequency of the external bias is comparable to this energy window, the real part of the dynamical conductance shows a series of plateaus that are well correlated with the profile of the transmission coefficient. The number and positions of the plateaus can be varied by changing the frequency. At frequencies much smaller than ∆E, the phase of the dynamical conductance is well described by the emittance. As the frequency is increased, the capacitivelike and inductivelike behaviors observed at off-resonance and on-resonance, respectively, are enhanced.