| Role of endogenous angiotensin II on sympathetic reflexes in conscious rabbits. | |
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MedLine Citation:
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PMID: 9227595 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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In the present study we sought to determine the contribution of endogenous brain stem angiotensin to renal sympathetic reflexes in conscious rabbits. Initial studies determined the subtype of receptor involved in the pressor response to angiotensin II (ANG II) administration into the fourth ventricle (4V). The AT1 antagonist losartan (0.001-10 micrograms 4V) had no effect on blood pressure alone but caused a dose-dependent blockade of the pressor effect of ANG II, with complete blockade produced by 10 micrograms, an effect that lasted for at least 3 h. The AT2 antagonist PD-123319 (0.1-1,000 micrograms) and vehicle had no effect on the ANG II pressor response. The effect of losartan (10 micrograms) on the baroreceptor, chemoreceptor, and trigeminal reflexes was examined in eight rabbits that had been implanted with 4V catheters and an electrode for recording renal sympathetic nerve activity (RSNA) 1 wk earlier. Baroreflex assessments were made during normoxia and two conditions of hypoxia (10% O2 and 10% O2 + 3% CO2) before and after 10 micrograms losartan or vehicle, on separate experimental days. During normoxia and hypoxia+CO2 losartan increased resting RSNA, the range, and upper plateau of the RSNA-MAP baroreflex curves. By contrast the marked increase in RSNA due to activation of trigeminal afferents was not affected by losartan. In conclusion the effect of losartan to increase RSNA activity in conscious rabbits, particularly during hypoxia and baroreceptor unloading, suggests that endogenous ANG II via AT1 receptors normally inhibits renal sympathetic baroreceptor and chemoreceptor reflexes. |
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Authors:
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R D Bendle; S C Malpas; G A Head |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: The American journal of physiology Volume: 272 ISSN: 0002-9513 ISO Abbreviation: Am. J. Physiol. Publication Date: 1997 Jun |
Date Detail:
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Created Date: 1997-08-18 Completed Date: 1997-08-18 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0370511 Medline TA: Am J Physiol Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: R1816-25 Citation Subset: IM |
Affiliation:
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Baker Medical Research Institute, Prahran, Victoria, Australia. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Angiotensin II
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pharmacology,
physiology* Animals Anoxia / blood, physiopathology Antihypertensive Agents / pharmacology Baroreflex / drug effects, physiology Biphenyl Compounds / pharmacology Blood Pressure / drug effects Cardiovascular System / drug effects Dose-Response Relationship, Drug Female Hemodynamics / drug effects Imidazoles / pharmacology Kidney / innervation* Losartan Male Nasopharynx / drug effects, physiology Pyridines / pharmacology Rabbits Reflex / physiology* Sympathetic Nervous System / drug effects, physiology* Tetrazoles / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Antihypertensive Agents; 0/Biphenyl Compounds; 0/Imidazoles; 0/Pyridines; 0/Tetrazoles; 11128-99-7/Angiotensin II; 114798-26-4/Losartan; 130663-39-7/PD 123319 |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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