From Citizendium - Reading time: 1 min
In biochemistry, cyclic AMP is an "adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH."[1]
In signal transduction, cell surface receptors may activate second messenger systems such as adenyl cyclase-cyclic AMP and cyclic GMP which then may activate protein kinases which then affect downstream targets (see figure).[2]
Cyclic AMP, along with pyrophasphate, are formed by action of the enzyme adenylate cyclase on adenosine triphosphate (ATP).
The medication adenosine inhibits the effects intracellular cyclic AMP thus reducing sympathetic stimulation.[3]