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
Related Documents :
9104859 - Doublet potentiation during eccentric and concentric contractions of cat soleus muscle.
12591019 - Reversible conduction block in isolated frog sciatic nerve by high concentration of bup...
7804519 - Resting and action potentials of nonischemic and chronically ischemic human ventricular...
3957639 - Somatosensory evoked potentials to muscle percussion in humans: upper extremity.
3942879 - Induction of the action potential in innervated slow muscle fibers of the frog. effects...
21391799 - Changes in knee biomechanics after a hip-abductor strengthening protocol for runners wi...
9104859 - Doublet potentiation during eccentric and concentric contractions of cat soleus muscle.
3631709 - Compound-action potentials of myelinated fibers in the saphenous nerve of the dog: in s...
20159139 - Ulnar neuropathy with normal electrodiagnosis and abnormal nerve ultrasound.
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.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
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


Previous Document:  Epicardial mesothelial cells synthesize and release endothelin.
Next Document:  Hemodynamic, neurohumoral, and myocardial energetic effects of pimobendan, a novel calcium-sensitizi...