Vascular smooth muscle cell cAMP signaling pathway

The **vascular smooth muscle cell cAMP signaling pathway** is not a single molecular target but rather a complex intracellular signal transduction cascade. It is initiated when extracellular ligands—such as catecholamines acting on β2-adrenoceptors or prostacyclin on IP receptors—activate Gs-protein coupled receptors on the surface of vascular smooth muscle cells. This activation stimulates adenylyl cyclase to convert ATP into cyclic AMP (cAMP). Elevated intracellular cAMP activates downstream effectors like protein kinase A (PKA) and exchange proteins directly activated by cAMP (Epac), leading to phosphorylation events that inhibit myosin light chain kinase activity. The net result is reduced phosphorylation of myosin light chains, decreased actin-myosin interaction, lowered cytosolic calcium concentration or sensitivity, and ultimately **relaxation** of the vascular smooth muscle—causing vasodilation rather than contraction. This pathway plays an essential role in regulating blood vessel tone under physiological conditions. Pharmacologically targeting this cascade with agents such as β2-adrenoceptor agonists or phosphodiesterase inhibitors can induce vasodilation for therapeutic purposes in diseases like hypertension or angina pectoris. However, because "vascular smooth muscle cell cAMP signaling pathway" refers to an entire network rather than an individual druggable entity such as a receptor or enzyme subunit, it should not be considered a canonical therapeutic target itself but instead represents multiple potential targets within its components—including GPCRs like β2-adrenoceptor and enzymes like adenylyl cyclases or phosphodiesterases[1][6]. "Unlike the heart, an increase in cAMP in vascular smooth muscle causes reduced contraction... The Gs-protein coupled pathway in smooth muscle stimulates adenylyl cyclase... which catalyzes formation of cAMP... MLCK is inhibited by cAMP." [1] "The level of cAMP is regulated by AC [adenylyl cyclase] and PDE [phosphodiesterase]. During the process AC is activated by G-alpha... As the figure shows, cAMP acts directly on three main targets: PKA... Epac... CNGCs." [6] In summary: this entry describes a **signaling mechanism**, not an individual molecule/receptor/protein suitable for direct drug targeting nomenclature standards. For structured data extraction purposes it should be flagged as incorrect for use where only discrete molecular entities are valid entries.

Other names

VSMC cAMP pathwayVascular smooth muscle cyclic AMP signalingcAMP-mediated vasodilation in vascular smooth muscle

Drugs that increase intracellular cAMP levels promote relaxation of vascular smooth muscle by inhibiting myosin light chain kinase activity through PKA activation and/or by opening potassium channels to hyperpolarize the cell membrane and reduce calcium influx[1][3].