Hypertension, the endothelium and the pathogenesis of chronic vascular disease.

The endothelium lines all vessels of the body and is the most important structure for communication between the flowing blood and the vessel wall. Healthy endothelium has antiadhesive and antithrombotic properties and is crucial for maintaining blood flow. It serves as a permeability barrier and prevents noxious agents from entering the vessel wall. Endothelial cells have secretory functions and secrete vasorelaxant substances. Therefore, functioning endothelium sustains the homoeostasis of the vessel wall. Endothelial functions are impaired by risk factors for cardiovascular disease such as hypertension, hyperlipidemia and hyperglycemia. Hypertension leads to decreased generation of nitric oxide in endothelial cells, thereby diminishing their vasorelaxant properties. Hypertension also contributes to an increase in endothelial cell permeability leading to intimal edema. Thirdly, hypertension increases the expression of adhesion molecules and increases the adherence of leukocytes to the vessel wall. Hence, hypertension directly contributes to the pathological alterations of the endothelium and it seems that these effects initiate and accelerate the pathogenesis of chronic vascular disease.