Potent contractile actions of prostanoid @entity7699 -receptor agonists on XXXX isolated pulmonary artery.

@entity1 @entity2871 @entity548 @entity43507 @entity1421 @entity2 @entity396 @entity7699 @entity6002 @entity7701 @entity2647 @entity58219 @entity73320 @entity7700 @entity4338 @entity49316 @entity10573
1. In 13 of 15 experiments, @entity1421 ( @entity1421 ) and @entity6002 (a prostanoid @entity7700 agonist) contracted isolated rings of @entity1 pulmonary artery at low concentrations (> or = 5 and > or = 0.5 nM respectively). Tissue was obtained from @entity1 undergoing surgery mainly for @entity2 . Characterization of the receptors involved was complicated by loss of sensitivity to the contractile PGE action over the experimental period. In contrast, contractile responses to @entity4338 , @entity2647 and the specific @entity2871 (TP-) receptor agonist, U-46619, did not decrease with time. 2. The relative contractile potencies for seven PGE analogues, measured during the first few hours after setting up the preparations, were as follows: @entity6002 > @entity396 = gemeprost > or = @entity1421 > or = @entity73320 > @entity10573 > or = 11-deoxy PGE1. This ranking indicates that an @entity7699 -receptor is involved. 3. The contractile action of @entity6002 was not blocked by the TP-receptor antagonists, EP 169 and @entity49316 , and the EP1-receptor antagonist, @entity43507 . 4. In two experiments, @entity1421 (50 nM) reduced basal tone and @entity6002 was a weak contractile agent. @entity2647 -induced tone was also inhibited by @entity1421 (EC50 = 5-20 nM), 11-deoxy PGE1 and butaprost (a selective @entity7701 -receptor agonist); the latter prostanoids were about 2 and 4 times less potent than @entity1421 respectively. Interactions with @entity2647 were different in experiments where @entity1421 alone was contractile: @entity1421 induced contraction superimposed on the @entity2647 response and 11-deoxy PGE1 induced either further contraction or had no effect. Butaprost produced relaxation at high concentrations;this may not be an @entity7701 action since preparations were highly sensitive to relaxant actions of prostacyclin (IP-) receptor agonists (cicaprost and @entity58219 ).5 The study has shown that in the majority of experiments on the @entity1 isolated pulmonary artery,the contractile @entity7699 system outweighed the relaxant @entity7701 system. However, in two experiments the reverse was true. It is not clear to what extent these differences are due to disease processes affecting the tissues.The findings are discussed in relation to the adverse cardiovascular responses occasionally encountered during treatment of postpartum @entity548 with @entity6002 , and more generally to the clinical use of EP-receptor agonists in @entity1 .
