Document Detail

Reactivity of isolated toad aortic rings to angiotension II: the role of nitric oxide.
MedLine Citation:
PMID:  19083004     Owner:  NLM     Status:  MEDLINE    
Little is known about the vascular actions of angiotensin II (Ang II) and nitric oxide (NO) in Amphibia. This study investigated (1) Ang II contractility, (2) NO concentrations, and (3) correlations between Ang II contractility, NO concentration and mean arterial pressure (MAP) in isolated Bufo arenarum toad aortic rings. Contractility was measured in isometric conditions, NO concentrations were determined by the Griess reaction, and MAP was determined by a direct method. In isolated toad aortic rings, Ang II produced a contractile response (292.7 +/- 89.2 mg; n = 20). Furthermore, a contractile response to norepinephrine (NE) was also obtained. A significant correlation between both the Ang II and NE contractile responses was found (r = 0.89; n = 11; P < 0.01). Administration of Ang II increased MAP values (Basal 16.8 +/- 1.7; n = 19 vs. Ang II 28.4 +/- 1.8 mmHg; n = 19; P < 0.001), and the increase of MAP by Ang II was positively correlated with the Ang II contractile response (P < 0.01). Administration of L-NAME also increased MAP values, and this effect was higher in those toads that presented a lower pressure response to Ang II (Pearson r = -0.68; P < 0.05). NO was present in all aortic rings, and its concentrations were negatively related to the Ang II contractile response (P < 0.036) and pressure response (Pearson r = -7.08; P < 0.001). These findings suggest that, in the B. arenarum toad, the NO system contra-regulates both the contractile and pressure Ang II responses, although its action could be different in each specimen.
Rodrigo O Marañón; Claudio M Joo Turoni; Alfredo Coviello; María Peral de Bruno
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-12-14
Journal Detail:
Title:  Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology     Volume:  179     ISSN:  1432-136X     ISO Abbreviation:  J. Comp. Physiol. B, Biochem. Syst. Environ. Physiol.     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-04-21     Completed Date:  2009-07-16     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8413200     Medline TA:  J Comp Physiol B     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  403-9     Citation Subset:  IM    
Departmento Biomédico, Facultad de Medicina, Universidad Nacional de Tucumán, INSIBIO-CONICET, Tucumán, Argentina.
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MeSH Terms
Analysis of Variance
Angiotensin II / metabolism,  pharmacology*
Anura / metabolism*
Aorta / drug effects*
Blood Pressure / drug effects
Isometric Contraction / drug effects
NG-Nitroarginine Methyl Ester / pharmacology
Nitric Oxide / metabolism*
Nitrites / analysis
Norepinephrine / pharmacology
Reg. No./Substance:
0/Nitrites; 10102-43-9/Nitric Oxide; 11128-99-7/Angiotensin II; 50903-99-6/NG-Nitroarginine Methyl Ester; 51-41-2/Norepinephrine

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