Document Detail


Thromboxane A2 does not act at the carotid sinus to mediate cardiovascular, adrenocorticotropin, cortisol, or blood gas responses.
MedLine Citation:
PMID:  9635149     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Thromboxane A2 (TxA2), well known as a vasoconstrictor and activator of platelets, also stimulates reflex cardiovascular, pituitary, adrenocortical, and blood gas responses, although the site of action is unknown. Previously we determined that the site of these actions is perfused by the carotid vasculature. The purpose of the present study was to test the hypothesis that TxA2 stimulates these responses by acting at the carotid sinus. The TxA2 mimetic U46619 (1 microgram.kg-1.min-1) or saline was infused into the carotid artery (CA) or vena cava in conscious, chronically instrumented carotid sinus denervated (CSD) or sham-operated sheep. Mean arterial pressure increased in all groups receiving U46619. Heart rate increased only in the CSD group receiving CA infusions of U46619. Adrenocorticotropic hormone (ACTH) and cortisol increased in the sham and CSD groups receiving CA U46619, and responses were not different between sham and CSD groups. PaCO2 values were higher in all CSD treatment groups compared with sham treatment groups. Arterial pH increased and PaCO2 decreased in both the sham and CSD groups in response to CA U46619. Although PaCO2 values were higher overall in the CSD group, the magnitude of change in response to U46619 infusions was similar in sham and CSD animals. There was no difference in pHa between CSD and sham groups. Hematocrit and PaO2 did not change. We conclude that TxA2 does not act at the carotid sinus, as responses to U46619 infusions in CSD animals were not different in the cases of ACTH, cortisol, and blood gases, or were enhanced rather than diminished in the case of heart rate. These findings support a hypothesis that TxA2 acts at the brain to mediate cardiovascular, pituitary, adrenocortical, and blood gas responses.
Authors:
T A Cudd
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Canadian journal of physiology and pharmacology     Volume:  76     ISSN:  0008-4212     ISO Abbreviation:  Can. J. Physiol. Pharmacol.     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-08-21     Completed Date:  1998-08-21     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0372712     Medline TA:  Can J Physiol Pharmacol     Country:  CANADA    
Other Details:
Languages:  eng     Pagination:  118-24     Citation Subset:  IM    
Affiliation:
Department of Physiology, University of Florida, Gainesville 32610-0274, USA. tcudd@cvm.tamu.edu
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MeSH Terms
Descriptor/Qualifier:
Adrenocorticotropic Hormone / drug effects*,  metabolism
Animals
Blood Pressure / drug effects
Carbon Dioxide / blood
Cardiovascular System / drug effects*
Carotid Sinus / drug effects*,  metabolism
Female
Heart Rate / drug effects
Hydrocortisone / metabolism*
Oxygen / blood
Prostaglandins / metabolism
Sheep
Thromboxane A2 / pharmacology*
Time Factors
Chemical
Reg. No./Substance:
0/Prostaglandins; 124-38-9/Carbon Dioxide; 50-23-7/Hydrocortisone; 57576-52-0/Thromboxane A2; 7782-44-7/Oxygen; 9002-60-2/Adrenocorticotropic Hormone

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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