Cyclic AMP.

Cyclic AMP is believed to be the intracellular agent which mediates the action of many hormones on their target cell. The mechanisms by which the nucleotide controls glycogen metabolism in liver and skeletal muscle seem to be firmly established. Data relevant to this area of research are selectively reviewed. In addition, the evidence is reviewed for and against a role for cyclic AMP in the regulation of a variety of other cellular functions including: cardiac contractility, smooth muscle relaxation, platelet aggregation, salivary gland amylase secretion, pancreatic exocrine secretion, and gastric acid secretion.