title: Angiotensin II and bradykinin: interactions between two centrally active peptides.
abstract: Two neuropeptides, bradykinin (BK) and angiotensin II (ANG II), produce an increase in blood pressure when injected into the brain ventricles. This study is an example of central peptide-peptide interaction and was carried out to determine if BK and ANG II share a common mechanism in the brain to control blood pressure and drinking in rats. Prior injection of saralasin [10 micrograms intraventricularly (ivt)] was found to enhance the pressor response to ivt BK (5 micrograms) by 44%. The same dose of saralasin attenuated the pressor response to ivt ANG II (200 ng) by 55%. 50 ng ANG II and 5 micrograms BK given together ivt did not significantly alter blood pressure or urine conductance compared to 50 ng ANG II alone. Drinking to ivt infusions of ANG II (14 ng/min) was significantly attenuated when combined with BK (0.7 micrograms or 2.8 micrograms/min). Pretreatment with 10 micrograms indomethacin ivt diminished the pressor response to 5 micrograms ivt BK. Prostaglandin E2 (1.4 micrograms/min), but not prostaglandin A2, inhibited drinking to 14 ng/min ivt infusions of ANG II. The results suggest that ANG II and BK share an interrelationship with respect to their central actions: ANG II inhibits the BK pressor response and BK acts to inhibit drinking induced by ANG II. Prostaglandins of the E series may mediate these central actions of bradykinins.
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D001920:Bradykinin / Q000494:pharmacology*; D002216:Captopril / Q000494:pharmacology; D004231:Diuresis / Q000187:drug effects; D004326:Drinking / Q000187:drug effects; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects*; D007213:Indomethacin / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012504:Saralasin / Q000494:pharmacology
chemical_list: D000804:Angiotensin II; D002216:Captopril; D012504:Saralasin; D001920:Bradykinin; D007213:Indomethacin