Introduction

The endothelium is one of the most intensively studied tissues in cellular mechanotransduction. It is the interface between blood (or lymph) and the underlying vessel walls in arteries, microcirculatory beds, veins, and lymphatics. Mechanotransduction is of particular significance in high-pressure, high-flow arteries where considerable blood flow forces act on the endothelium lining the inner boundaries of the vessel walls. Consequently, endothelial mechanotransduction is studied principally as a flow-mediated mechanism.

Efficient vascular transport systems are central to the evolutionary success of all higher organisms. Throughout phylogeny there is a consistent pattern of structural relationships in branching vessels. For example, much of the mammalian arterial circulation obeys mathematical relationships of vessel geometry that ensure a continuum of flow characteristics (volumetric, velocity, flow profile, and shear relationships), where the major distributing arteries repeatedly branch to provide blood to the complex volume of widely dispersed tissues and organs throughout the body; Murray’s Law [1, 3] and Zamir’s Law [2] are examples. Similar relationships are found in fluid transport systems of primitive marine animals. General principles such as these reflect the interdependence of flow with vessel structure and function throughout evolution that ensures the efficient and successful distribution of fluid in primitive life forms and blood circulation in mammals.