Noradrenaline, also known as norepinephrine, is a substance primarily used in the sympathetic or orthosympathetic nervous system as a neurotransmitter. Its role is to relay messages via the nerves to different parts of the body during many different physiological processes. Similar to adrenaline, another transmitter of the sympathetic nervous system
, noradrenaline induces different effects depending on which receptors bind with it. Of these many effects, noradrenaline notably acts to reduce the diameter of certain blood vessels, increase the frequency of heart beats, and can also cause an increase in blood pressure when the need arises. One of its principal effects is to enable the contraction of certain organs, tending to slow bowel function.