Cyclic nucleotide second messengers (cAMP and cGMP) play a central role in signal
transduction and regulation of physiologic responses. Their intracellular levels are
controlled by the complex superfamily of cyclic nucleotide phosphodiesterase (PDE)
enzymes. Continuing advances in our understanding of the molecular pharmacology of
these enzymes has led to the development of selective inhibitors as therapeutic agents for
disease states ranging from cancer and heart failure to depression and sexual dysfunction …