Document Detail

Changes in vascular reactivity following administration of isoproterenol for 1 week: a role for endothelial modulation.
MedLine Citation:
PMID:  16702995     Owner:  NLM     Status:  MEDLINE    
1. The aim of this study was to assess the effects of treatment with isoproterenol (ISO, 0.3 mg kg-1 day-1, s.c.) for 7 days on the vascular reactivity of rat-isolated aortic rings. Additionally, potential mechanisms underlying the changes that involved the endothelial modulation of contractility were investigated. 2. Treatment with ISO induced cardiac hypertrophy without changes in haemodynamic parameters. Aortic rings from ISO-treated rats showed an increase in the contraction response to phenylephrine (PHE) and serotonin, but did not change relaxations produced by acetylcholine or isoproterenol. Removal of the endothelium increased the responses to PHE in both groups. However, this procedure was less effective in ISO-treated as compared with control rats. Endothelial cell removal abolished the increase in the response to PHE in ISO-treated rats. The presence of Nomega-nitro-L-arginine methyl ester shifted the concentration-response curve to PHE to the left in both groups of rats. However, this effect was more pronounced in the ISO group. In addition, aminoguanidine (50 microM) potentiated the actions of PHE only in the ISO group. ISO treatment increased nitric oxide synthase (NOS) activity and neuronal NOS and endothelial NOS protein expression in the aorta. 3. Neither losartan (10 microM) nor indomethacin (10 microM) abolished the effects of ISO on the actions of PHE. Superoxide dismutase (SOD, 150 U ml-1) and L-arginine (5 mM), but neither catalase (300 U ml-1) nor apocynin (100 microM), blocked the effect of ISO treatment. In addition, we observed an increase in superoxide anion levels as measured by ethidium bromide fluorescence and of copper and zinc superoxide dismutase protein expression in ISO-treated rats. 4. In conclusion, our data suggest that ISO treatment alters the endothelial cell-mediated modulation of the contraction to PHE in rat aorta. The increased maximal response of PHE seems to be due to an increase in superoxide anion generation, which inactivates some of the basal NO produced and counteracts NO-mediated negative modulation even in the presence of high NO production and antioxidant defence.
Ana Paula C Davel; Elisa Mitiko Kawamoto; Cristoforo Scavone; Dalton V Vassallo; Luciana V Rossoni
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Publication Detail:
Type:  Comparative Study; Evaluation Studies; In Vitro; Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-05-15
Journal Detail:
Title:  British journal of pharmacology     Volume:  148     ISSN:  0007-1188     ISO Abbreviation:  Br. J. Pharmacol.     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-03     Completed Date:  2006-12-26     Revised Date:  2013-06-07    
Medline Journal Info:
Nlm Unique ID:  7502536     Medline TA:  Br J Pharmacol     Country:  England    
Other Details:
Languages:  eng     Pagination:  629-39     Citation Subset:  IM    
Department of Physiology and Biophysics, Institute of Biomedical Sciences, ICB, University of São Paulo, Av. Professor Lineu Prestes, 1524, sala 101B, 05508-900 São Paulo, SP, Brazil.
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MeSH Terms
Antioxidants / metabolism
Aorta, Thoracic / drug effects
Blood Pressure / drug effects
Blood Vessels / drug effects*
Endothelium, Vascular / drug effects*,  physiology*
Heart Rate / drug effects
Heart Ventricles / drug effects
Isoproterenol / administration & dosage*
Nitric Oxide Synthase / metabolism
Organ Size / drug effects
Phenylephrine / pharmacology
Rats, Wistar
Signal Transduction
Superoxides / metabolism
Vasoconstriction / drug effects
Vasoconstrictor Agents / metabolism
Reg. No./Substance:
0/Antioxidants; 0/Vasoconstrictor Agents; 11062-77-4/Superoxides; 59-42-7/Phenylephrine; 7683-59-2/Isoproterenol; EC Oxide Synthase

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