In this chapter, we have demonstrated that dopamine receptor subtypes are expressed on airway smooth muscle (ASM) and modulates ASM function. We detected the expression of dopamine D1 and D2 receptors in ASM. Dopamine D1 receptor agonist stimulated cAMP production in human ASM cells and dose- dependently relaxed guinea pig ASM. Acute activation of the dopamine D2 receptor in human ASM cells inhibited forskolin-stimulated adenylyl cyclase activity. On the other hand, chronic activation of the dopamine D2 receptor stimulated it, and potentiated forskolin-induced guinea pig ASM relaxation. These findings suggest that functional dopamine D1 and D2 receptors are expressed in ASM, and modulate ASM tone through adenylyl cyclase/cAMP signaling.
- Adenylyl cyclase
- Airway smooth muscle