FR190997, a novel bradykinin B2 agonist, expresses longer action than bradykinin in paw edema formation and hypotensive response.

Biological actions of a novel non-peptide B2 receptor agonist, FR190997, were examined by comparing them with those of bradykinin. The paw edema was induced by subcutaneous injection of 30 microl of solution of bradykinin (0.3, 0.6, and 1.2 nmol) or FR190997 (0.1, 0.3, and 0.9 nmol) into the right hind paw of ICR male mice. Bradykinin caused a dose-dependent edema formation, which peaked at 15 min and ceased after 150 min. FR190997 also formed a dose-dependent edema, peaking at 15-30 min with a slight delay compared to bradykinin and this response continued over 200 min. The edema formed by bradykinin or FR190997 was inhibited by pretreatment with HOE140 (1 mg/kg) injected intraperitoneally 30 min before the injection of each agonist. A novel non-peptide B2 antagonist, FR173657 (30 mg/kg, i.p. 30 min before the agonist), also diminished these responses by bradykinin and FR190997 dose-dependently. Indomethacin (10 mg/kg, i.p. 30 min before) inhibited the response to FR190997, suggesting that release of prostaglandins induced by the B2 agonistic action might be involved in this inflammatory process induced by FR190997. The hypotensive action of FR190997 was also examined. Intravenously injected FR190997 caused the systemic hypotensive response in Sprague-Dawley male rats anesthetized with pentobarbital. The potency of FR190997 was weaker than that of bradykinin, when compared with the maximal hypotension. Duration of the hypotensive response of FR190997 was significantly longer than that of bradykinin. These results indicate that FR190997 has the B2 agonistic action similar to bradykinin and is also a good tool for in vivo examination of the B2 receptor.