The vascular endothelium paves the entire inner surface of the blood vessels that permeate every organ of our bodies. It is essentially the “Grand Canal” through which oxygen, nutrients, and other chemical stimuli travel to reach the cells that comprise our tissues. Although originally viewed as a passive boundary layer that interfaces with blood, the endothelium is now known to be a key integrator in human physiology, and to play a central role in control of thrombosis and the inflammatory response. The growth of new blood vessels by microvascular endothelium through angiogenesis and vasculogenesis also is critical for the development of all normal organs, in addition to contributing to the etiology of many diseases, including cancer, atherosclerosis, arthritis, and macular degeneration. Thus, understanding of vascular control can have a fundamental impact on biology and medicine.

Because biology has been dominated by a focus on genomics and molecular biochemistry over the past 50 years, there has been an enormous increase in our understanding of the molecules and genes that contribute to control of endothelial cell (EC) function. Cogent descriptions of these molecules and the important roles they play can be found in other chapters in this volume. However, in addition to being a conduit for transfer of chemical factors, the endothelium is also constantly exposed to mechanical stresses that influence its form and function. In particular, physical forces associated with changes in blood pressure, wall tension, and fluid shear stresses have been found to regulate various signal transduction pathways, change cytoskeletal structure, and alter gene expression in ECs, as well as modulate the angiogenic response (1–3).