Methods of Endothelial Function Assessment: Description and Applications

Introduction

The endothelium is a monolayer of cells, called endothelial cells, that lines the interior of blood vessels, including arteries, veins and cardiac chambers, acting as a protective layer between circulating blood and other tissues. The endothelium is crucial for the control of vascular homeostasis, and is involved in the regulation of intracellular signaling, vascular tonus and permeability, coagulation cascade and angiogenesis, among others. One of the main activities of the endothelium is the release of autocrine and paracrine substances in response to stimuli. Injuries to the endothelium trigger an inflammatory response with participation of several cell types – lymphocytes, monocytes, platelets and smooth muscle cells – culminating in endothelial cell dysfunction, stiffness of vessel wall and atherosclerotic plaque formation.

Endothelial dysfunction is an early, key characteristic of development and progression of atherosclerotic plaque and subsequent complications. This is characterized by a reduced bioavailability of endothelium-derived vasodilators, such as nitric oxide (NO), along with a relative or absolute increase in available vasoconstrictors. Such unbalanced condition impairs the endothelium-dependent vasodilation, a functional marker of endothelial dysfunction.

[…]