Mechanotransduction of flow-induced shear stress by endothelial glycocalyx fibers is torque determined.

To test the hypothesis that the mechanotransduction of flow-induced shear stress on endothelial cells (ECs) might be triggered by the total torque transmitted from the glycocalyx fibers to the ECs rather than by the total shear force acting directly on the membrane of ECs, we formulated the arterial wall as a five-layer model and numerically investigated the effect of two types of damages to the endothelial glycocalyx layer (EGL) on the flow in the EGL and on the drag force and bending moment acting on the glycocalyx fibers. One type of damage was to alter the thickness of the EGL, and the other was to damage its integrity. The results revealed that almost all amount of the shear stress acting on ECs was transmitted to the cells by the EGL and that the flow-induced shear stress acting directly on the cell membrane was negligibly small. In addition, the total force transmitted from the glycocalyx fibers to the cell membrane in the forms of drag force was hardly affected by the damages to the EGL. However, such damages could significantly influence the total torque at the roots of the EGL fibers. In conclusion, the mechanotransduction of shear stress by the EGL might be torque determined rather than force determined.