L-arginine is a conditionally essential essential amino acid primarily involved in metabolism, urea excretion, and DNA synthesis.    L-arginine is important for growth hormone production (stimulating the pituitary gland), sperm production (participating in sperm and seminal fluid), wound healing (stimulating collagen formation), improving a person's sensitivity to insulin, improving muscle tone, and maintaining healthy blood pressure levels as a means of producing nitric oxide.    L-arginine is the primary component used as a base for the formation of nitric oxide.