Mechanisms of vascular injury: the emerging role of the endothelium.

Evidence is increasing that vascular tone is highly dependent on the health of the endothelium and on the delicate balancing act between endothelium-derived relaxing and endothelium-derived contracting factors. Moreover, there is also evidence supporting the notion that the same factors which affect vascular tone also regulate, either in an autocrine or paracrine fashion, changes in vascular architecture. Synthesis and release of both endothelium-derived relaxing and contracting factors are affected by a number of physiologic and therapeutic agents as well as by other factors, among them vascular injury in disease states such as atherosclerosis, hypertension, diabetes, and acute renal failure. A number of trials indicate that therapeutic intervention may be capable of modulating the synthesis and release of these substances and the balance between the two as well as influencing the processes which control vascular remodeling.