Phenylephrine

(R)-(-)-Phenylephrine is a selective α₁-adrenoceptor agonist primarily used as a decongestant. In Vitro: (R)-(-)-Phenylephrine is a selective α₁-adrenoceptor agonist with pK_i values of 5.86, 4.87 and 4.70 for α_1D, α_1B and α_1A receptors respectively^[1][2]. Phenylephrine promotes cardiac fibroblast proliferation. Phenylephrine activates CaN and evokes NFAT3 nuclear translocation. It suggests that the Ca(²⁺)/CaN/NFAT pathway mediates phenylephrine -induced cardiac fibroblast proliferation, and this pathway might be a possible therapeutic target in cardiac fibrosis^[3]. In Vivo: Perfusion of hearts with 100 μM phenylephrine causes a rapid (maximal at 10 min) 12-fold activation of two p38-MAPK isoforms. α₁-adrenoceptor agonists such as phenylephrine increase the contractility of the heart. Phenylephrine also activates SAPKs/JNKs in neonatal ventricular myocytes^[4]. Phenylephrine could increase the alveolar fluid clearance in high tidal volume-ventilated rats and accelerate the absorption of pulmonary edema^[5].