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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1976-4-19
pubmed:abstractText
In conscious trained dogs, administration of bromazepam (0.3 mg/kg p.o.) or diazepam (0.3 and 1.0 mg/kg p.o.) had no influence on heart rate. A higher dose (10 mg/kg p.o.) of two benzodiazepines elicited a positive chronotropic effect which was rapid in onset and of long duration. The beta-adrenoceptor blocking agent practolol (2.5 mg/kg i.v.) did not revert heart rate after the benzodiazepines to the same level as in controls, indicating that the tachycardia was not produced by an increase in sympathetic outflow to the heart. For diazepam, a sympathetic--parasympathetic interaction cannot be excluded. However, diazepam and bromazepam significantly reduced the tachycardia which is normally observed after administration of methylatropine (0.5 mg/kg i.v.) alone or in combination with practolol. In anaesthetized dogs, bromazepam failed to modify the heart rate responses to electrical stimulation of cardiac vagal or sympathetic nerves, excluding an action on this compound on ganglionic transmission and cardiac cholinoceptors and adrenoceptors. It is concluded that high doses of diazepam and bromazepam influence the heart rate of conscious dogs in a biphasic way. Firstly, they cause a central reduction of vagal tone to the heart resulting in tachycardia. Secondly, the two drugs decrease the cardiac pacemaker rate directly. Since the overall effect is tachycardia, the central action is more pronounced.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0014-2999
pubmed:author
pubmed:issnType
Print
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
361-8
pubmed:dateRevised
2003-11-14
pubmed:meshHeading
pubmed:year
1976
pubmed:articleTitle
Analysis of cardiac chronotropic responses to diazepam and bromazepam in conscious trained dogs.
pubmed:publicationType
Journal Article