Document Detail

Reduction of ventricular fibrillation threshold by histamine: resolution into separate H1- and H2-mediated components.
MedLine Citation:
PMID:  6128405     Owner:  NLM     Status:  MEDLINE    
The effects of histamine and the selective agonists impromidine (H2-agonist) and 2-(2-thiazolyl ethylamine)(H1-agonist) on ventricular fibrillation threshold were tested in the isolated guinea-pig heart. All three compounds produced reversible concentration-dependent decreases in ventricular fibrillation threshold. Ventricular fibrillation threshold reduction was not secondary to the positive chronotropic effect of the three compounds. Computer analysis of the data using appropriate theoretical models suggests that the net effect of histamine on ventricular fibrillation threshold is the resultant of two components: H1 and H2. Pyrilamine inhibited the H1-mediated effects of histamine on ventricular fibrillation threshold with a Kb value of 0.449 nM. H1- and H2-receptors mediating ventricular fibrillation threshold reduction differ in their relative sensitivity to histamine (H1 greater than H2; EC50 for histamine, 53.9 nM at H1- and 311 nM at H2-receptors) and in the maximum response which they are capable of producing (H1 congruent to 1/2 that of H2). The finding that extremely low concentrations of histamine (less than 1 pg/ml) can effectively reduce ventricular fibrillation threshold reinforces the concept that histamine is highly arrhythmogenic.
J P Trzeciakowski; R Levi
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Publication Detail:
Type:  In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of pharmacology and experimental therapeutics     Volume:  223     ISSN:  0022-3565     ISO Abbreviation:  J. Pharmacol. Exp. Ther.     Publication Date:  1982 Dec 
Date Detail:
Created Date:  1983-01-27     Completed Date:  1983-01-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0376362     Medline TA:  J Pharmacol Exp Ther     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  774-83     Citation Subset:  IM    
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MeSH Terms
Guinea Pigs
Heart Rate / drug effects
Histamine / pharmacology*
Histamine H1 Antagonists / pharmacology
Histamine H2 Antagonists / pharmacology
Models, Cardiovascular
Receptors, Histamine / physiology*
Receptors, Histamine H1 / drug effects,  physiology*
Receptors, Histamine H2 / drug effects,  physiology*
Ventricular Fibrillation / physiopathology*
Grant Support
20091//PHS HHS
Reg. No./Substance:
0/Histamine H1 Antagonists; 0/Histamine H2 Antagonists; 0/Receptors, Histamine; 0/Receptors, Histamine H1; 0/Receptors, Histamine H2; 51-45-6/Histamine

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

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