Nitric oxide released from vascular endothelium causes relaxation of the underlying smooth muscle.
In addition, it inhibits adhesion of platelets and white cells to the endothelium and in experimental models it protects against atherogenesis. We have used pharmacological tools to probe the role of this molecule in humans. We went on to demonstrate that patients with hypertension and insulin dependent diabetes appear to have deficient nitric oxide-mediated dilatation of the arterial circulation. Leiper J, MacAllister R, Whitley G, Santa Maria J, Chubb A, Charles I, Vallance P. Identification of two human dimethylarginine dimethylaminohydrolases with distinct tissue distributions and homology to microbial arginine deiminases. Leiper J. DDAH 1 and DDAH 2 encode asymmetric methyl aminohydrolases with distinct expression patterns in adult and fetal tissues and are located on chromosomes 1p22 and 6p21.3 respectively.