Tussive activity of inhaled PGD2 in the cat and characterisation of the receptor(s) involved.

Prostaglandin D2 (PGD2) and some naturally occurring and synthetic prostaglandin (PG) analogues were evaluated for irritant/ tussive activity in cats. PGD2, PGF2 alpha and ICI81008 were potent tussive agents when inhaled, producing both an early and late phase of coughing. In addition all three prostaglandins decreased respiratory rate. In contrast PGE2, PGE1 and PGA1 were 100-1000 times less potent than PGF2 alpha as irritants and weakly stimulated respiratory rate. The PGE class of compounds only produced an early phase of coughing. The rank order of early phase tussive activity was ICI81008 greater than PGF2 alpha greater than PGF2 beta much greater than PGE1 = PGE2 = PGA1. This rank order is similar to that characterising the prostanoid 'X' contractant or class II receptor(s).