Pharmacological characterization of postjunctional α-adrenoceptors in human nasal mucosa

Background: Functional alpha(1)- and alpha(2)-adrenoreceptor subtype pharmacology was characterized in an in vitro human nasal mucosa contractile bioassay. Methods: Nasal mucosa was obtained from 49 donor patients and mucosal strips were placed in chambers filled with Krebs-Ringer solution and attached to isometric force transducers. Results: Nonselective a-adrenoreceptor agonists epinephrine, norepinephrine, and oxymetazoline produced concentration-dependent contractions of isolated human nasal mucosa (pD(2) = 5.2, 4.9, and 6.5, respectively). The alpha 2-adrenoreceptor agonist BHT-920 (10 mu M)-induced contractions were blocked by yohimbine (0.01-1 mu M) and prazosin (0.01-1 mu M) inhibited the contractile response to the alpha(1)-adrenoreceptor agonist phenylephrine (10 AM). Histological analysis showed that phenylephrine and BHT-920 differentially contracted the arteries and veins of human nasal mucosa, respectively. Conclusion: Our results indicate that functional alpha(1)- and alpha(2)-adrenoceptors are present and functional in human nasal mucosa. The alpha(2)-adrenoceptors display a predominant role in contracting the veins and the alpha(1)-adrenoceptors appear to preferentially constrict the human nasal arteries.