Phosphodiesterase 3, Phosphodiesterase 4, and Phosphodiesterase 5 (typically considered separately: "Phosphodiesterase 3", "Phosphodiesterase 4", "Phosphodiesterase 5") (PDE3, PDE4, PDE5)

Phosphodiesterase 3, 4, and 5 are three distinct enzymes from the larger phosphodiesterase superfamily that regulate intracellular signaling by degrading cyclic nucleotides (cAMP and/or cGMP)[4][7]. Each isoform has a unique tissue distribution and substrate specificity: PDE3 hydrolyzes both cAMP and cGMP, but is inhibited by cGMP; PDE4 is specific for cAMP; and PDE5 is specific for cGMP[4][7]. Drugs targeting these enzymes are used in the treatment of diseases such as heart failure (PDE3), pulmonary disease and psoriasis (PDE4), and erectile dysfunction and pulmonary arterial hypertension (PDE5)[3][1][8]. Notably, PDE3, PDE4, and PDE5 are not a single molecular entity and should be considered separately; listing them together is not scientifically precise[4][1][7].

Other names

PDE3: cGMP-inhibited phosphodiesterasePDE4: cAMP-specific phosphodiesterasePDE5: cGMP-specific phosphodiesterase

Inhibition of PDE3, PDE4, or PDE5 increases intracellular levels of cAMP (PDE3, PDE4) or cGMP (PDE5), leading to smooth muscle relaxation, vasodilation, anti-inflammatory and other effects depending on tissue distribution[8][7] - PDE3 inhibition: positive inotropy, vasodilation, antiplatelet[1][8] - PDE4 inhibition: anti-inflammatory, bronchodilation[8] - PDE5 inhibition: vasodilation, relaxation of cavernosal smooth muscle[8]