CYCLIC NUCLEOTIDE PHOSPHODIESTERASES

Often casually referred to simply as phosphodiesterases. Multiple isoenzymes are known. PDE-I is calcium/calmodulin regulated and important in CNS and vasorelaxation, PDE-II is cGMP-stimulated and hydrolyzes cAMP. PDE-III regulates vascular and airway dilation, platelet aggregation, cytokine production and lipolysis; PDE-IV (inhibited by rolipram) is important in control of airway smooth muscle and inflammatory mediator release but also has a role in CNS and in regulation of gastric acid secretion. PDE-V and VI are cGMP-specific. PDE-V is involved in platelet aggregation; PDE-VI is regulated by interaction with transducin in photoreceptors. PDE-VII is abundant in skeletal muscle and present in heart and kidney.