Protease-activated receptor-2 peptides activate neurokinin-1 receptors in the mouse isolated trachea.

Protective roles for protease-activated receptor-2 (PAR(2)) in the airways including activation of epithelial chloride (Cl(-)) secretion are based on the use of presumably PAR(2)-selective peptide agonists. To determine whether PAR(2) peptide-activated Cl(-) secretion from mouse tracheal epithelium is dependent on PAR(2), changes in ion conductance across the epithelium [short-circuit current (I(SC))] to PAR(2) peptides were measured in Ussing chambers under voltage clamp. In addition, epithelium- and endothelium-dependent relaxations to these peptides were measured in two established PAR(2) bioassays, isolated ring segments of mouse trachea and rat thoracic aorta, respectively.