Nitric oxide: A compound that is toxic but which, paradoxically, plays a number of important roles in the body, including the following:
- It acts as a vasodilator (blood vessel relaxant).
- It therefore controls blood flow to tissues.
- It regulates the binding and release of oxygen to hemoglobin.
- It thereby controls the supply of oxygen to mitochondria (cell powerhouses that generate energy).
- It kills parasitic organisms, virus-infected cells, and tumor cells (by inactivating respiratory chain enzymes in their mitochondria).
- It stimulates the production of new mitochondria.