Central action of bradykinin (I) Electroencephalogram of bradykinin and its degradation system in rat brain.

Abstract

Both in vivo and in vitro experiments were performed to elucidate the relationship between the action of bradykinin (BK) and the possibility of release of pharmacologically active fragments from BK in the rat brain. In in vivo experiments, the activities of EEG increased immediately after the intracerebral administration of 5 nmol BK. The effect was prolonged by intracerebral pretreatment of ortho-phenanthroline which inhibits plasma kinases. In vitro experiments, ortho-phenanthroline inhibited partially purified enzyme of rat brain which released fragments of BK possessing phenylalanine, serine, proline and/or arginine as N-terminal amino acids. Only arginine and minute amounts of phenylalanine were observed after the incubation with ortho-phenanthroline. The inhibition of the enzyme by ortho-phenanthroline prolonged the excited phase produced by BK on the EEG and on behavior. Ser-Pro containing fragments derived from BK are concerned with the sedative phase of BK which was observed after the excitative stage.