A comparison of the contractile activity fo PGD2 and PGF2α on human isolated bronchus

Prostaglandins may be implicated in the bronchoconstriction which occurs in asthma. Prostaglandins F_2α (PGF_2α and D₂ (PGD₂) have been reported to produce bronchoconstriction in asthmatic subjects in vivo and PGF_2α cotnracts human isolated airway smooth muscle. We examined the relative efficacy and potency of PGF_2α and PGD₂ on human bronchial spiral strips taken from 6 patients at thoracotomy. PGF_2α had greater efficacy than PGD₂. The mean % T_max (percentage of maximal contractile response) ± s.e. mean were 84 ± 7 and 54 ±7 respectively (P < 0.05). PGF_2α (mean pD₂ ± s.e. mean = 6.39 ± 0.6) tended to be more potent than PGD₂ (5.68 ± 0.2). Since, in vivo, PGD₂ has greater efficacy and potency than PGF_2α, our results suggest that the in vivo effect of these prostaglandins does not result solely from an action on airway muscle.