Actions and interactions of bradykinin, prostaglandins, and nonsteroidal antiinflammatory agents on the eye

Abstract

Intracameral injections of bradykinin into the eyes of rabbits anesthetized with urethane were found to produce a dose-dependent constriction of the pupil and increase in the amount of protein present in the aqueous humor. Both these effects were relatively fast in onset, pupillary constriction being observed 1–2 min after the injection. The intact bradykinin molecule was required to produce these effects since prior incubation of known amounts of bradykinin with chymotrypsin and subsequent intracameral injection were without effect. No kininase activity was observed in samples of normal aqueous humor, however, kininase activity was present in aqueous humor removed from eyes inflamed by either paracentesis or nitrogen mustard. The actions of bradykinin on both the pupil and the protein content of aqueous humor were markedly reduced or abolished by pretreatment with inhibitors of prostaglandin biosynthesis, such as indomethacin or pirprofen, given either topically or by intraperitoneal injection. In these animals the simultaneous injection of prostaglandin Ez together with the bradykinin restored the ocular responses to normal. These results suggest that prostaglandins contribute to the ocular actions of bradykinin.