Oscillatory pressurization of an animal cell as a poroelastic spherical body

The analytical solution of a spherical poroelastic body under an oscillatory hydrostatic pressurization is obtained. This solution is then parameterized and interpreted in terms of a spherical animal cell with the cytoskeleton serving as the solid phase. It is found that for a cell with free or nearly free membrane leakage (such as in the case of an osteocytic cell body), the induced pore fluid pressure amplitude near the center of the cell exceeds the amplitude of the applied pressure by 50% if the loading frequency falls near that of normal human gait (1 Hz). A parametric analysis shows that the leakage coefficient is proportional to the intrinsic permeability ratio between the boundary and the bulk matrix. The physiological implication of the solution is further interpreted and discussed through an anatomical analysis of two representative cellular entities under compression: a chondrocyte and an osteocytic cell body. Finally, through a comparison between the characteristic time of gait and the characteristic pore fluid pressure relaxation times of various fluid-saturated entities in the body (such as a tumor, the brain, the cortical bone, the trabecular bone, and the cartilage, etc.), it is found that the gait-induced pore fluid transport seems to be important only in deeply buried cells and the mineralized cartilage.