EFFECTS OF AN ORALLY-ACTIVE NONPEPTIDE BRADYKININ B-2 RECEPTOR ANTAGONIST, FR173657, ON PLASMA EXUDATION IN RAT CARRAGEENAN-INDUCED PLEURISY

1 Effects of an orally active non-peptide (BK) B-2 receptor antagonist , FR173657 nyl)oxymethyl]phenyl]-N-methylaminocarbonylmethyl] acrylami de) on the plasma exudation in rat carrageenin-induced pleurisy were i nvestigated. 2 Plasma exudation induced by intrapleural injection of b radykinin (BK, 3 nmol per rat) into male SD strain rats (SPF, 8 weeks old) were significantly inhibited by oral administration of novel B-2 receptor antagonist FR173657 (3-30 mg kg(-1), 1 h before BK injection) in a dose-dependent manner, whereas that induced by histamine was not . 3 The inhibitory effect of 30 mg kg(-1) FR173657 persisted for more than 4 h. 4 Intrapleural injection of lambda-carrageenin (2% (w/v), 0. 1 ml per rat) caused marked plasma exudation and accumulation of exuda tes from 1 h after carrageenin injection. The maximum plasma exudation response was observed 5 h after carrageenin. The oral administration of FR173657 to rats (30 mg kg(-1), 1 h before carrageenin) significant ly (by 50-77%) blunted the plasma exudation 1, 3, 5, and 7 h after car rageenin, causing a significant parallel reduction (by 42-57%) in the volume of exudates. 5 The anti-inflammatory effect of FR173657 on rat carrageenin-induced pleurisy was almost equipotent with that of the pe ptide B-2 antagonist Hoe140 (1 mg kg(-1), i.v.), a plasma kallikrein i nhibitor, soy bean trypsin inhibitor (0.3 mg per rat, intrapleural inj ection) and bromelain (10 mg kg(-1), i.v.). 6 In pleurisy induced by i ntrapleural injection of a histamine releaser, compound 48/80, the pla sma exudation was observed only within 20 min after the injection. Thi s plasma exudation was not affected by FR173657, although it was compl etely inhibited by a mixture of pyrilamine (5 mg kg(-1), i.v.) and met hysergide (3 mg kg(-1), i.v.). 7 These results indicate that FR173657 is an orally active, promising anti-inflammatory agent for kinin-depen dent inflammation.