Phenylephrine HCl is a selective agonist of α₁-adrenergic receptor [1].?

α₁-adrenergic receptors are one of the three main families of adrenergic receptors regulating the actions of? norepinephrine and epinephrine [1].?

Phenylephrine exhibits significant selectivity for α₁-adrenergic receptors subtypes. When tested with hamster α_1B-AR, bovine α_1C-AR , and rat α_A/D-AR, Phenylephrine showed inhibition of I-BE binding with pK_i?values of 4.87, 4.70 and 5.86 for α_1B, α_1C?and α_A/D?receptors respectively and intrinsic activities of activating cloned α₁-adrenergic receptors subtypes with pEC50 values of? 6.47, 6.77 and 7.01 for α_1B, α_1C?and α_A/D?receptors respectively [1].?

In high?tidal?volume ventilated rats, ?although 1×10^-9 mol/L phenylephrine did not raise alveolar fluid clearance, alveolar space injection of phenylephrine at different concentrations of 1×10^-5, 1×10^-6, 1×10^-7 and 1×10^-8 increased the alveolar fluid clearance and promoted the absorption of pulmonary edema in a dose-dependent manner. [2].?

References:

[1]. Minneman KP, Theroux TL, Hollinger S, et al. Selectivity of agonists for cloned alpha 1-adrenergic receptor subtypes. Molecular Pharmacology. 1994, 46(5):929-36.

[2]. Li NJ, Gu X, Li W, et al. Effect of phenylephrine on alveolar fluid clearance in ventilator-induced lung injury. Chinese Medical Sciences Journal. 2013, 28(1):1-6.