Pressor action of angiotensin I at the ventrolateral medulla: effect of selective angiotensin blockade.
In this study we explored the possibility that angiotensin-(1-7) (Ang-(1-7)) is involved in the control of blood pressure at the rostral ventrolateral medulla (RVLM) by determining the effect of angiotensin antagonists (DuP 753 and A-779) and the effect of the angiotensin converting enzyme inhibitor, ramiprilat on the pressor action produced by angiotensin I (Ang I). The pressor effect produced by bilateral microinjection of Ang I into the RVLM of anesthetized rats was not significantly altered by DuP 753 or by the ACE inhibitor ramiprilat. Conversely, the Ang-(1-7) antagonist, A-779, reduced significantly the pressor effect produced by Ang I. These data suggest that in our experimental condition Ang I was preferentially converted to Ang-(1-7) at RVLM, or that Ang I and/or one of its fragments acts through a receptor blocked by A-779.
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Departamento de Fisiologia and Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.
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Oliveira
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Campagnole-Santos
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Khosla
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D000803:Angiotensin I / Q000008:administration & dosage / Q000494:pharmacology* / Q000502:physiology; D000804:Angiotensin II / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology; D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000494:pharmacology; D000818:Animals; D001713:Biphenyl Compounds / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology; D019808:Losartan; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects* / Q000502:physiology*; D008845:Microinjections; D010446:Peptide Fragments / Q000494:pharmacology / Q000502:physiology; D017257:Ramipril / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D011945:Receptors, Angiotensin / Q000502:physiology; D013777:Tetrazoles / Q000494:pharmacology
C092006:7-Ala-angiotensin (1-7); D057911:Angiotensin Receptor Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D001713:Biphenyl Compounds; D007093:Imidazoles; D010446:Peptide Fragments; D011945:Receptors, Angiotensin; D013777:Tetrazoles; D000804:Angiotensin II; C052549:ramiprilat; D000803:Angiotensin I; C118790:angiotensin I (1-7); D019808:Losartan; D017257:Ramipril