The electric potential, ion number concentration, and fluid velocity distributions induced by an ac electric field applied to a cell suspended in an electrolyte solution are numerically calculated, using a network simulation method. The cell model consists of a conducting internal medium surrounded by an insulating membrane and a charged permeable cell wall. The distributions obtained are used to calculate the dipole coefficient and the electrorotation velocity of the particles under the action of a rotating field. The results are first particularized to simple systems, leading to good agreement with existing theories. Then, the dependence of the rotation spectra of cells with some of the parameters is considered.