Bioelectrorheological model of the cell. 8. Cellular deformation under prolonged and recurrent shear stress

The influence of a prolonged and recurrent shear stress created by a periodic electric field on the mechanical properties of Neurospora crassa cells was investigated. Conditions were found under which modifications of cellular structures responding to stress become irreversible, and plastic flow of the viscoelastic structural elements is observed. The symmetry of the response of the cell under stress application and relaxation was lost, when compared to the reference conditions. To interpret the results a general rheological model was proposed. As previously described (Pawłowski et al., 1997), the existence of the three hypothetical supramolecular regions of the membrane (F, S and O) was suggested. Rheological parameters for the above regions were calculated. Theoretical functions were satisfactorily fitted to the experimental results.