Document Detail


Ionic basis of ventricular arrhythmias in remodeled rat heart during long-term myocardial infarction.
MedLine Citation:
PMID:  10533576     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Deleterious electrical abnormalities evolve during myocardial infarction. The goal of this study was to analyse current changes during the late decompensated phase of heart disease induced by coronary ligation and to compare them in various heart regions. METHODS: Young rats were submitted to left coronary ligature. After 4-6 months, cells were enzymatically dissociated and isolated from the upper part basal region of the left ventricle, as well as from the septum, apex and the right ventricle before being studied under whole-cell patch-clamp. RESULTS: Basal L-type Ca2+ current, ICaL elicited at +10 mV did not exhibit regional dependence neither in control nor after post-myocardial infarction (PMI). ICaL showed both a significantly reduced peak amplitude (17.1 +/- 2.8 pA/pF versus 9.9 +/- 1.4 pA/pF in seven control and seven PMI hearts, n = 32 and 40, respectively) and a slower inactivation, such that the amount of inward charges during a 200 ms-depolarizing pulse was nearly unchanged. beta-Adrenergic stimulation was less effective in increasing ICaL in PMI cells but it slowed inactivation further. Significant differences in the K+ currents were observed. A regional distribution was seen for Ito only, with the largest amplitude in the right ventricle (in pA/pF: 23.1 +/- 2.4, 18.2 +/- 3.9, 14.8 +/- 2.4, 8.3 +/- 1.7 in the right ventricle, apex, septum and left ventricle, respectively n = 8, 7, 8 and 9). This was also true in failing heart cells despite Ito being halved in each of the four regions (in pA/pF: 12.2 +/- 2.5, 11.2 +/- 1.9, 5.1 +/- 1.0 and 4.8 +/- 1.0, respectively n = 12, 12, 11 and 13). IK1 was also significantly reduced by 20% in the PMI cells. Two-way analyses of variance demonstrated the absence of interaction between the topographical origin of the cells and the physiological state of the rats. The alpha 1-adrenergic agonist, methoxamine significantly reduced Ito and IK1 to the same extent in both sham and PMI cells, by about 35% and 20% respectively. CONCLUSIONS: Long-term left coronary occlusion induces significant alterations in both Ca2+ and K+ currents that occur with similar amplitude in both ventricles. They include a marked reduction in Ito amplitude as well as a slowing of ICaL inactivation. Both factors could contribute to the disturbances in cellular electrical behaviour and the occurrence of arrhythmias in the post-myocardial infarcted heart.
Authors:
F Aimond; J L Alvarez; J M Rauzier; P Lorente; G Vassort
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cardiovascular research     Volume:  42     ISSN:  0008-6363     ISO Abbreviation:  Cardiovasc. Res.     Publication Date:  1999 May 
Date Detail:
Created Date:  1999-11-04     Completed Date:  1999-11-04     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0077427     Medline TA:  Cardiovasc Res     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  402-15     Citation Subset:  IM    
Affiliation:
Unité de Recherches INSERM U-390, CHU Arnaud de Villeneuve, Montpelier, France.
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MeSH Terms
Descriptor/Qualifier:
Action Potentials* / drug effects
Adrenergic alpha-Agonists / pharmacology
Adrenergic beta-Agonists / pharmacology
Analysis of Variance
Animals
Arrhythmias, Cardiac / etiology*,  pathology,  physiopathology
Biological Transport, Active* / drug effects
Blotting, Western
Calcium Channel Blockers / pharmacology
Calcium Channels / drug effects
Gene Expression
Ion Transport
Isoproterenol / pharmacology
Male
Methoxamine / pharmacology
Myocardial Infarction / complications*,  pathology,  physiopathology
Nifedipine / pharmacology
Patch-Clamp Techniques
Potassium Channels / drug effects,  genetics
Rats
Rats, Wistar
Time Factors
Ventricular Remodeling*
Chemical
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 0/Adrenergic beta-Agonists; 0/Calcium Channel Blockers; 0/Calcium Channels; 0/Potassium Channels; 21829-25-4/Nifedipine; 390-28-3/Methoxamine; 7683-59-2/Isoproterenol

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


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