Nitric oxide (NO) is a gas naturally found in the body that conveys information between cells. In the last decade researchers have found that NO is a signaling molecule of key importance for the cardiovascular system, regulating blood pressure and blood flow to different organs. In addition, discoveries surrounding nitric oxide's role as a principal neurotransmitter moderating erectile function, a pathophysiological negotiator and messenger in inflammation, and a weapon against infections have increased research attention across the fields of biochemistry, chemistry, molecular biology, gene therapy, cell biology, immunology, pharmacology, neuroscience, and physiology.