Factors and agents that influence the synthesis, metabolism and activity of cyclic AMP will be examined. An inhibitor of cyclic AMP will be purified and characterized. The possible interactions of cyclic AMP and cyclic GMP synthesis and accumulation will be studied. Cyclic AMP and cyclic GMP levels in clinical specimens (plasma and urine) will be examined in some endocrine and metabolic disorders in order to design new diagnostic tests and to examine the pathophysiology of some disorders.