Electrical remodeling of the ventricular myocardium in myocarditis: studies of rat experimental autoimmune myocarditis.
The purpose of this study was to evaluate the electrical remodeling of the ventricular myocardium in the experimental autoimmune myocarditis (EAM) model in Lewis rats. EAM was induced by immunization with cardiac myosin. During the active myocarditis phase, the effective refractory period (ERP), the duration of the monophasic action potential (MAPD) was extracted from the left ventricular free wall, and the mRNA levels of Kv1.4, 4.2, 4.3 and L type Ca2+ channel were determined by RNase protection assays. The inducibility of ventricular arrhythmia was higher in EAM rats than in the control rat, and the direct relationship between the coupling intervals of the premature stimulus and the ventricular arrhythmia in EAM rats. The ERP was prolonged in EAM rats compared with the control group. The MAPDs determined as 20% and 90% repolarization time, were both longer in EAM rats than in the controls. The level of expression of Kv4.2 mRNA was reduced in EAM rats in comparison with the controls, whereas those of Kv1.4, 4.3 and the L type Ca2+ channel were unchanged. Ventricular vulnerability was higher in EAM rats than in the control rats, and some of the ventricular arrhythmias observed in the EAM group seemed to be based on triggered activity. The level of expression of Kv4.2 mRNA was significantly reduced, and this change was compatible with prolongation of the action potential duration.
Saito
Junko
J
Department of Internal Medicine, Kitasato University School of Medicine, Sagamihara, Japan. jsaito@med.kitasato-u.ac.jp
Niwano
Shinichi
S
Niwano
Hiroe
H
Inomata
Takayuki
T
Yumoto
Yoshihiro
Y
Ikeda
Kazuko
K
Inuo
Kimiatsu
K
Kojima
Jisho
J
Horie
Minoru
M
Izumi
Tohru
T
D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D001327:Autoimmune Diseases / Q000503:physiopathology; D001794:Blood Pressure / Q000502:physiology; D004195:Disease Models, Animal; D004594:Electrophysiology; D005071:Evoked Potentials / Q000502:physiology; D007473:Ion Channels / Q000235:genetics; D009205:Myocarditis / Q000503:physiopathology*; D016133:Polymerase Chain Reaction; D051381:Rats; D011917:Rats, Inbred Lew; D012016:Reference Values; D013552:Swine; D013610:Tachycardia / Q000503:physiopathology; D018754:Ventricular Dysfunction / Q000503:physiopathology*; D016276:Ventricular Function / Q000502:physiology*
D007473:Ion Channels