Prostanoid receptors involved in the relaxation of human bronchial preparations

1 Iloprost and cicaprost (LP-receptor agonists) induced relaxations in the histamine- (50 mu M) contracted human bronchial preparations (pD(2) values, 6.63+/-0.12 and 6.86+/-0.08; E-max values, 90+/-04 and 65+/-08% of the pap averine response for iloprost (n=6) and cicaprost (n=3), respectively). 2 Prostaglandin E-2 (PGE(2)) and misoprostol (EP-receptor agonist) relaxed the histamine-contracted human bronchial preparations (pD(2) values, 7.13+/ -0.07 and 6.33+/-0.28; E-max values, 67+/-04 and 57+/-08% of the papaverine response for PGE(2) (n=14) and misoprostol (n=4), respectively). In additi on, both relaxations were inhibited by AH6809 (DP/EP1/EP2-receptor antagoni st; 3 mu M; n= 5-6). 3 The PGE(2)-induced relaxations of human bronchial preparations were not m odified by treatment with AH23848B (TP/EP4-receptor antagonist; 30 mu M; n= 4). 4 The contracted human bronchial preparations were significantly relaxed by prostaglandin D-2 (PGD(2)) or by BW245C a DP-receptor agonist. However, th ese responses did not exceed 40% of the relaxation induced by papaverine. I n addition, the relaxations induced by PGD(2) were significantly inhibited by treatment with a DP-receptor antagonist BWA868C (0.1 mu M; n= 3). 5 These data suggest that the relaxation of human isolated bronchial prepar ations induced bl prostanoids involved IP-, EP2- and to a lesser extent DP- receptors but not EP4-receptor.