IP

Prostaglandin receptor IP (prostacyclin receptor, PTGIR) is the primary receptor for prostacyclin (PGI₂) and belongs to the class A rhodopsin-like G protein-coupled receptor family, where it predominantly couples to Gs proteins and stimulates adenylyl cyclase-dependent cAMP production^[1][2]. Mechanistically, IP receptor activation promotes vascular smooth muscle relaxation, inhibits platelet aggregation, and contributes to vascular homeostasis through cAMP-mediated signaling pathways^[1][3]. Beyond its established cardiovascular functions, prostacyclin-IP signaling also regulates vascular smooth muscle cell differentiation and proliferation and participates in inflammatory processes that influence disease progression in distinct pathological contexts^[1][4]. In experimental and disease settings, altered prostacyclin signaling has been linked to pulmonary vascular disease, atherosclerosis, and inflammatory disorders, supporting the use of IP receptor modulation as a research framework for studying vascular remodeling and inflammation^[1][4][5]. Compared with other prostanoid receptor subtypes that preferentially recognize prostaglandins such as PGE₂, PGD₂, PGF₂α, or thromboxane-derived ligands, the IP receptor exhibits preferential responsiveness to prostacyclin and functions primarily as a relaxant prostanoid receptor that elevates intracellular cAMP signaling^[2][6]. The IP receptor has also been reported to exist in alternatively spliced isoforms that differ in their C-terminal regions and activate distinct downstream signaling responses, providing an additional level of biological specificity relative to related prostanoid receptors^[6]. For experimental applications, stable prostacyclin analogs and IP receptor agonists, including epoprostenol, iloprost, and treprostinil, are widely used to investigate prostacyclin-dependent signaling and vascular biology because endogenous PGI₂ is chemically unstable and rapidly degraded in vivo^[1][5][8].