The endothelium is a layer of cells that line the entire circulatory system. These cells are found on the inside of all blood vessels, and help increase or decrease blood flow and pressure by relaxing or constricting the vessels (referred to as vasodilation and vasoconstriction, respectively). These cells also help regulate the passage of materials in and out of blood vessels, and are involved in a number of important vascular processes including blood clotting and new blood vessel formation. Having a more flexible (reactive) endothelium is generally considered desirable for health, and, likewise, the endothelium is often compromised in individuals with cardiovascular disease. Patients with endothelial dysfunction tend to notice greater vasoconstriction, restricted blood flow, higher blood pressure, local inflammation, and reduced circulatory capacity. This may place them at greater risk for heart attack, stroke, or thrombosis (blood clot).
Endothelial cells are androgen responsive, which may partly account for men exhibiting less vascular reactivity than women. Similarly, anabolic/androgenic steroid use has been shown to impair endothelial activity and vascular reactivity. Studies at the University of Innsbruck in Austria compared the level of endothelial dilation in 20 steroid users to a group of control athletes. Those individuals using anabolic steroids noticed slight but measurably impaired vascular dilation and endothelial function. Additional studies at the University of Wales in Cardiff comparing vascular dilation in active, previous, and non-steroid users, also demonstrated anabolic steroids to cause a decline in endothelial-independent vasodilation. These effects leave the steroid user with more relative “stiffness” in the vascular system, which could increase the chance of an adverse cardiovascular event. In both studies, vascular reactivity improved after the discontinuance of anabolic/androgenic steroids.
Wlliam Llewellyn (2011) - Anabolics