Document Detail


Brainstem oxytocinergic modulation of heart rate control in rats: effects of hypertension and exercise training.
MedLine Citation:
PMID:  19638362     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Oxytocinergic brainstem projections participate in the autonomic control of the circulation. We investigated the effects of hypertension and training on cardiovascular parameters after oxytocin (OT) receptor blockade within the nucleus tractus solitarii (NTS) and NTS OT and OT receptor expression. Male spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats were trained (55% of maximal exercise capacity) or kept sedentary for 3 months and chronically instrumented (NTS and arterial cannulae). Mean arterial blood pressure (MAP) and heart rate (HR) were measured at rest and during an acute bout of exercise after NTS pretreatment with vehicle or OT antagonist (20 pmol of OT antagonist (200 nl of vehicle)(-1)). Oxytocin and OT receptor were quantified ((35)S-oligonucleotide probes, in situ hybridization) in other groups of rats. The SHR exhibited high MAP and HR (P < 0.05). Exercise training improved treadmill performance and reduced basal HR (on average 11%) in both groups, but did not change basal MAP. Blockade of NTS OT receptor increased exercise tachycardia only in trained groups, with a larger effect on trained WKY rats (+31 +/- 9 versus +12 +/- 3 beats min(1) in the trained SHR). Hypertension specifically reduced NTS OT receptor mRNA density (-46% versus sedentary WKY rats, P < 0.05); training did not change OT receptor density, but significantly increased OT mRNA expression (+2.5-fold in trained WKY rats and +15% in trained SHR). Concurrent hypertension- and training-induced plastic (peptide/receptor changes) and functional adjustments (HR changes) of oxytocinergic control support both the elevated basal HR in the SHR group and the slowing of the heart rate (rest and exercise) observed in trained WKY rats and SHR.
Authors:
Keila T Higa-Taniguchi; Jorge V C Felix; Lisete C Michelini
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-07-28
Journal Detail:
Title:  Experimental physiology     Volume:  94     ISSN:  1469-445X     ISO Abbreviation:  Exp. Physiol.     Publication Date:  2009 Nov 
Date Detail:
Created Date:  2009-10-19     Completed Date:  2009-12-30     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  1103-13     Citation Subset:  IM    
Affiliation:
Department of Physiology & Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, SP, Brazil.
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MeSH Terms
Descriptor/Qualifier:
Animals
Blood Pressure / physiology
Brain Stem / anatomy & histology,  physiology*
Heart Rate / physiology*
Hypertension / genetics,  physiopathology*
In Situ Hybridization
Male
Oxytocin / genetics,  physiology*
Physical Conditioning, Animal / physiology
RNA, Messenger / biosynthesis,  genetics
Rats
Rats, Inbred SHR
Rats, Inbred WKY
Receptors, Oxytocin / genetics,  physiology*
Rest / physiology
Chemical
Reg. No./Substance:
0/RNA, Messenger; 0/Receptors, Oxytocin; 50-56-6/Oxytocin

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


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