Central and peripheral effects of bradykinin and prostaglandin E2 on blood pressure in conscious rats.

Bradykinin or prostaglandin E2 (PGE2), when injected intravenously, decreased blood pressure of conscious rats in a dose-dependent manner, while intracerebroventricular injections of bradykinin or PGE2 caused a dose-dependent increase in blood pressure. SQ 14,225, an inhibitor of angiotensin converting enzyme, potentiated the central pressor or peripheral depressor effect of bradykinin. Indomethacin, an inhibitor of prostaglandin synthesis, almost completely inhibited the central pressor effect of bradykinin when injected intraventricularly. Indomenthacin, when injected intravenously, failed to inhibit the peripheral depressor effect of bradykinin, whereas it significantly attenuated the peripheral depressor effect of bradykinin when the angiotensin converting enzyme was inhibited with SQ 14,225. These results suggest that the central pressor effect of bradykinin is mainly mediated by the synthesis of prostaglandins in the central nervous system, while only a small fraction of peripheral depressor effect of bradykinin is, at least in conscious rats, mediated by the synthesis of prostaglandins in the systemic circulation.