Document Detail


Effects of magnesium on polymorphic ventricular tachycardias induced by aconitine.
MedLine Citation:
PMID:  7532749     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We examined the effects of Mg2+ on aconitine-induced polymorphic ventricular tachycardias (PVT) in excised rabbit hearts under Langendorff perfusion and in Purkinje-muscle preparations. Local electrograms using bipolar electrodes and transmembrane potentials with the microelectrode technique were recorded from Langendorff hearts and Purkinje-muscle preparations, respectively. In Langendorff preparations, intracoronary application of 0.1 microM aconitine induced PVT 28.8 +/- 3.4 min after development of regular monomorphic ventricular tachycardias (MVT) in all 18 preparations. Application of 5 and 10 mM Mg2+ restored aconitine-induced PVT to sinus rhythm after 26.8 +/- 3.4 min (n = 9), but < 3 mM Mg2+ was not effective in restoring of sinus rhythm. Increased Mg2+ concentrations < or = 5 mM in the coronary perfusate prevented development of PVT by aconitine. Intracoronary application of 10 microM tetrodotoxin (TTX) also restored aconitine-induced PVT to sinus rhythm after 3.2 +/- 0.8 min (n = 4). Although applications of 50 microM lidocaine, 10 microM flecainide, or 1 microM verapamil could change PVT to MVT, they were not effective in restoring sinus rhythm. In Purkinje-muscle preparations, spontaneous action potentials (AP) from slow diastolic depolarization appeared after aconitine at the maximum diastolic potential of -75.0 +/- 3.7 mV in Purkinje fibers and were conducted to ventricular muscles (n = 5). Spontaneous activity gradually increased in rate and then developed triggered activity arising from early after depolarization (EAD). EAD induced by aconitine always appeared first in Purkinje fibers and later in muscle fibers. Once triggered activities started from EAD, rate, rhythm and amplitudes of APs became fast and variable.(ABSTRACT TRUNCATED AT 250 WORDS)
Authors:
H Adaniya; H Hayami; M Hiraoka; T Sawanobori
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Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  Journal of cardiovascular pharmacology     Volume:  24     ISSN:  0160-2446     ISO Abbreviation:  J. Cardiovasc. Pharmacol.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1995-03-30     Completed Date:  1995-03-30     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7902492     Medline TA:  J Cardiovasc Pharmacol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  721-9     Citation Subset:  IM    
Affiliation:
Department of Cardiovascular Diseases, Tokyo Medical and Dental University, Japan.
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MeSH Terms
Descriptor/Qualifier:
Aconitine / toxicity*
Animals
Anti-Arrhythmia Agents / pharmacology,  therapeutic use
Electrophysiology
Heart / drug effects*,  physiopathology
Heart Ventricles / drug effects,  metabolism
Magnesium / administration & dosage,  pharmacology,  therapeutic use*
Microelectrodes
Purkinje Fibers / drug effects*,  metabolism
Rabbits
Tachycardia, Ventricular / chemically induced,  drug therapy*
Tetrodotoxin / pharmacology,  therapeutic use
Chemical
Reg. No./Substance:
0/Anti-Arrhythmia Agents; 302-27-2/Aconitine; 4368-28-9/Tetrodotoxin; 7439-95-4/Magnesium

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


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