Catecholamines

Fate of Circulating CatecholaminesSmall amounts of catecholamines are released into the circulation continuously; much more material is secreted in spurts, in response to sympathetic nervous impulses, hypoglycemia, stress and other physiologic stimuli. Because of the low concentrations of norepinephrine and epinephrine in the blood, it had been very difficult to study the fate of circulating catecholamines until Axelrod and his collaborators at the National Institute of Mental Health developed the use of isotopically labeled materials for this purpose. The fate of the tiny amounts of catecholamine released tonically into the circulation can now be monitored by use of continuous . . .