Phosphodiesterase type III enzyme (PDE3)

Phosphodiesterase type III (PDE3) enzymes are a subfamily of cyclic nucleotide phosphodiesterases that hydrolyze the second messengers cAMP and cGMP, playing a crucial role in regulating their intracellular concentrations. PDE3 is unique among PDEs as it is a cGMP-inhibited, cAMP-specific phosphodiesterase: it preferentially hydrolyzes cAMP but its activity can be inhibited by increased levels of cGMP. The mammalian PDE3 family consists of two genes: PDE3A and PDE3B. These enzymes regulate key physiological processes including cardiac contractility, vascular tone, and platelet aggregation. Inhibitors targeting PDE3 are used therapeutically as positive inotropes/vasodilators for acute heart failure management and for peripheral vascular disease or intermittent claudication treatment. However, long-term use of some PDE3 inhibitors has been associated with increased mortality due to arrhythmias or other adverse effects.

PDE3 inhibitors increase intracellular cAMP leading to enhanced cardiac contractility and vasodilation.