[Cyclic nucleotide phosphodiesterase in vertebrates].

The cellular concentration of cyclic nucleotides is largely dependent upon the activity of the enzymatic system responsible for their degradation: cyclic nucleotide phosphodiesterase. This enzymatic system thus plays a crucial role in the regulation of the multiple functions which are modulated by cyclic nucleotides in the organism. Many methodological problems, as well as the complexity of the phosphodiesterase system have long maintained a confusion in this field. Recent progresses (purification to homogeneity of some enzymatic forms, discovery of regulatory mechanisms, particularly) have brought a considerable evolution in the knowledge of the system. It is now well established that cyclic nucleotide phosphodiesterase exists under several isoenzymatic forms, the properties and distribution of which largely differ from a tissue to another. Some of these forms are relatively well characterized, while the representativity of others is still discussed. The significance of this multiplicity of isoenzymes, and their interrelationships are presently under study. A very interesting aspect in the study of this enzymatic system is that it is submitted to several physiological regulatory processes. Recent studies on this point suggest that phosphodiesterase might play a major role in the response of the organism to several hormones. These fundamental studies of phosphodiesterase system find a most interesting application in the pharmacological field. Indeed, numerous synthetic compounds which inhibit the enzyme present a strong pharmacological interest.