Adaptive responses of vascular wall to fluid shear stress induced by blood flow

The adaptive responses of the vascular wall to blood flow changes determine the flow-radius relationship in the vessel tree. The in vivo experiments using the arterie-venous shunt or partial occlusion of the artery demonstrated that the biomechanical factor inducing such responses is the wall shear stress elicited by blood flow. The in vitro experiments employing cultured vascular endothelial cells clarified that the endothelial cell has the sensing mechanism to the fluid shear stress inducing the response of intracellular free Ca⁺⁺ (the second messenger of the internal signalling system) and the information transmitted to organielles modify not only the function and morphology of the endothelium but also those of the smooth muscle cells.