Catecholamines

CATECHOLAMINES are low-molecular-weight substances that contain a catechol nucleus and an amine group (Fig. 1 ). Two such compounds, norepinephrine and epinephrine, are synthesized and secreted by mammalian tissues and serve important functions in neural and endocrine integration, the first primarily as a neurohumor and the second as a hormone. A third catecholamine, dopamine, is highly localized in certain organs, and may have physiologic functions in addition to its role as the immediate precursor of norepinephrine. Catecholamines are synthesized in the brain and in the sympathetic nerve endings and chromaffin cells of peripheral tissues. Norepinephrine and epinephrine are secreted into the . . .