Reduction in baroreceptor reflex response by angiotension III and its modification by Ile7-angiotensin III and bestatin in the rat.
We evaluated the participation of endogenous brain angiotensin III (AIII) in central cardiovascular regulation, using the intracerebroventricular injection technique in Sprague-Dawley rats anesthetized with pentobarbital sodium (50 mg/kg, i.p.). AIII (100 pmol) promoted an elevation in systemic arterial pressure and a reduction in the baroreceptor reflex (BRR) response. Its specific antagonist, Ile7-AIII (100 nmol), and the aminopeptidase inhibitor, bestatin (200 nmol), on the other hand, augmented the response of the same reflex. The suppressive action of AIII (100 pmol) on the BRR was attenuated, and the enhancing effect of Ile7-AIII (100 nmol) was potentiated, however, when these two peptides were administered simultaneously with bestatin (200 nmol). All these events were significantly different from their controls during the first 10-15 min following injection, parallel to the time course of a discernible action of AIII on systemic arterial pressure. We discussed that the endogenous AIII in the central nervous system may participate in cardiovascular control by tonically inhibiting the BRR, in concert with other brain neuropeptides.
Lin
K S
KS
Department and Institute of Pharmacology, National Yang-Ming Medical College, Taipei, Taiwan.
Chan
J Y
JY
Chan
S H
SH
D000804:Angiotensin II / Q000031:analogs & derivatives*; D000805:Angiotensin III / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects; D007276:Injections, Intraventricular; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D010656:Phenylephrine / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013997:Time Factors
D000804:Angiotensin II; D000805:Angiotensin III; D010656:Phenylephrine; C056764:angiotensin III, Ile(7)-; D007930:Leucine; C012211:ubenimex