cGMP-specific 3',5'-cyclic phosphodiesterase (PDE5) (PDE5)

Phosphodiesterases (PDEs) are a superfamily of enzymes responsible for the degradation of the second messengers cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). In smooth muscle cells, these enzymes serve as critical regulators of vascular tone, airway resistance, and organ motility by controlling the termination of cyclic nucleotide signaling pathways (Source: PubMed, PMID: 15507021). The most therapeutically significant isoform in smooth muscle is cGMP-specific 3',5'-cyclic phosphodiesterase (PDE5), which is highly expressed in the corpus cavernosum, pulmonary vasculature, and vascular smooth muscle (Source: UniProt, O76074). By hydrolyzing cGMP, PDE5 opposes the vasodilatory effects of the nitric oxide (NO) pathway. Pharmacological inhibition of PDE5 leads to increased cGMP levels, promoting protein kinase G (PKG) activation and subsequent smooth muscle relaxation (Source: StatPearls, NBK549843). This mechanism is widely utilized in the clinical management of erectile dysfunction and pulmonary arterial hypertension. Other isoforms, such as PDE3 and PDE4, also contribute to smooth muscle regulation in the heart and lungs, respectively, and represent targets for treating heart failure and chronic obstructive pulmonary disease (Source: PubChem).

Other names

Phosphodiesterase 5PDE5AcGMP-specific phosphodiesterase type 5PDE5

Inhibition of the PDE5 enzyme prevents the hydrolysis of cGMP to 5'-GMP. This leads to the accumulation of cGMP, which activates protein kinase G (PKG). PKG subsequently reduces intracellular calcium levels and decreases the sensitivity of the contractile apparatus to calcium, resulting in smooth muscle relaxation and vasodilation (Source: StatPearls, NBK549843).