Document Detail

Cardiovascular effects of NaCl microinjections into the nucleus of the solitary tract.
MedLine Citation:
PMID:  8050035     Owner:  NLM     Status:  MEDLINE    
The nucleus of the solitary tract (NTS) was systematically explored in the alpha-chloralose-anesthetized rat for sites that elicited changes in mean arterial pressure (MAP) and heart rate (HR) during microinjections (20 nl) of phosphate-buffered saline (PBS; pH 7.2-7.4) or NaCl solutions containing various concentrations of NaCl (104-326 mM). Decreases in MAP (range 7-83 mmHg) and HR (range 10-70 bpm) were consistently elicited from sites in the caudal medial and commissural subnuclei of NTS. Microinjection of PBS or NaCl into other NTS subnuclei or area postrema did not elicit cardiovascular responses. Microinjection of LiCl in PBS elicited cardiovascular responses that were significantly smaller than those elicited by microinjection of NaCl in PBS at the same NTS site. Injections of either a hyperosmotic (400 mOsm/kg) or a hyposmotic (204 mOsm/kg) solution of mannitol into NaCl-sensitive sites did not elicit cardiovascular responses. Finally, most of the sites in NTS that elicited cardiovascular responses during microinjection of glutamate (1 M) did not respond to microinjections of PBS. Administration of atropine methyl bromide had no effect on the magnitude of the depressor response to injections of PBS into NTS, but significantly attenuated (32%) the HR response. Subsequent administration of the ganglionic blockers hexamethonium bromide or arfonad abolished both the depressor and bradycardic responses. These data suggest that within a restricted region of the caudal NTS there exists a pool of neurons sensitive to changes in extracellular Na+ concentrations that, when activated by the sodium, elicit vasodepressor responses as a result of sympathoinhibition and bradycardia as a result of vagal excitation and sympathoinhibition.
S L Hochstenbach; J Ciriello
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Brain research     Volume:  644     ISSN:  0006-8993     ISO Abbreviation:  Brain Res.     Publication Date:  1994 May 
Date Detail:
Created Date:  1994-09-08     Completed Date:  1994-09-08     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0045503     Medline TA:  Brain Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  233-42     Citation Subset:  IM    
Department of Physiology, Health Sciences Centre, University of Western Ontario, London, Canada.
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MeSH Terms
Atropine / pharmacology
Blood Pressure / drug effects
Heart Rate / drug effects
Hemodynamics / drug effects*
Hexamethonium Compounds / pharmacology
Lithium / pharmacology
Parasympathetic Nervous System / cytology,  drug effects
Rats, Wistar
Sodium Chloride / administration & dosage,  pharmacology*
Solitary Nucleus / anatomy & histology,  physiology*
Stereotaxic Techniques
Sympathetic Nervous System / cytology,  drug effects
Reg. No./Substance:
0/Hexamethonium Compounds; 51-55-8/Atropine; 7439-93-2/Lithium; 7647-14-5/Sodium Chloride

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