Simulation of motor-driven cochlear outer hair cell electromotility

We propose a three-dimensional (3D) model to simulate outer hair cell elect romotility. In our model, the major components of the composite cell wall a re explicitly represented. We simulate the activity of the particles/motor complexes in the plasma membrane by generating active strains inside them a nd compute the overall response of the cell. We also consider the constrain ed wall and compute the generated active force. We estimate the parameters of our model by matching the predicted longitudinal and circumferential ele ctromotile strains with those observed in the microchamber experiment. In a ddition, we match the earlier estimated values of the active force and cell wall stiffness. The computed electromotile strains in the plasma membrane and other components of the wall are in agreement with experimental observa tions in trypsinized cells and in nonmotile cells transfected with Prestin. We discover several features of the 3D mechanism of outer hair cell electr omotilty. Because of the constraints under which the motors operate, the mo tor-related strains have to be 2-3 times larger than the observable strains . The motor density has a strong effect on the electromotile strain. Such e ffect on the active force is significantly lower because of the interplay b etween the active and passive properties of the cell wall.