Catecholamines

THE catecholamines — dopamine, adrenaline (epinephrine) and noradrenaline (norepinephrine) — are found at specific locations in tissues. Noradrenaline is present mainly in the sympathetic nerves of the peripheral and central nervous systems and acts locally on effector cells of vascular smooth muscle, adipose tissue, liver, heart and brain as a neurotransmitter. Adrenaline is primarily located in the adrenal medulla and acts mainly as a hormone on distant target organs after its release from the adrenal gland into the bloodstream. Dopamine has two functions: it serves as a precursor of noradrenaline, and it presumably functions as a neurotransmitter in the areas . . .