Linked Life Data

10545309

Source:http://linkedlifedata.com/resource/pubmed/id/10545309

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2000-1-12
pubmed:abstractText
Evidence from animal studies suggests that beta-blockers can act within the central nervous system to increase cardiac vagal motoneuron activity. We have attempted to determine whether such an effect is evident in healthy humans, by examining the effects of lipophilic and hydrophilic agents on heart rate variability and cardiac vagal reflexes. A total of 20 healthy volunteers took part in the study. Autonomic studies were performed after 72 h of treatment with placebo, atenolol or metoprolol in a blinded cross-over design. ECG recordings were taken at rest and during mental and orthostatic stress. Heart rate variability was measured in the time and frequency domains. The effects on heart rate of two opposing cardiac vagal reflexes were examined. Trigeminal stimulation causing vagal stimulation, and isometric forearm muscle contraction ('muscle heart reflex') causing vagal inhibition, were performed alone and simultaneously. At rest, during mental stress and during trigeminal stimulation, beta-blocker therapy was associated with significantly increased high-frequency beat-to-beat heart rate variability when compared with placebo. There were no significant differences in effects on heart rate or heart rate variability between atenolol and metoprolol. Analysis of the muscle heart reflex, alone and with simultaneous trigeminal stimulation, showed that the magnitude of the R-R interval response was significantly greater after beta-blocker therapy compared with placebo, but the effects of atenolol and metoprolol were equivalent. beta-Blocker therapy increased cardiac vagal activity, as shown by measures of high-frequency heart rate variability and reflex studies. Lipophilic and hydrophilic beta-blockers appeared to be equally efficacious in increasing the cardiac vagal modulation of heart rate.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0143-5221
pubmed:author
pubmed:issnType
Print
pubmed:volume
97
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
585-93; discussion 609-10
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1999
pubmed:articleTitle
Use of opposing reflex stimuli and heart rate variability to examine the effects of lipophilic and hydrophilic beta-blockers on human cardiac vagal control.
pubmed:affiliation
Departments of Cardiovascular Medicine and Physiology, University of Birmingham, Edgbaston, Birmingham B15 2TH, U.K. j.c.vaile@bham.ac.uk
pubmed:publicationType
Journal Article, Clinical Trial, Randomized Controlled Trial, Research Support, Non-U.S. Gov't