antiarrhythmic-peptide and Arrhythmias--Cardiac

Topics: Amino Acid Sequence; Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Gap Junctions; Molecular Sequence Data; Oligopeptides

The aim of this study is to observe the effect of combined amiodarone and antiarrhythmic peptide (AAP10) use on the incidence of induced ventricular arrhythmias in healed myocardial infarction (MI) rabbits.. Twenty Japanese rabbits underwent thoracotomy without coronary artery ligation (Sham, group A), the middle left circumflex branch were ligated to induce MI in 180 Japanese rabbits. Eight weeks after operation, 124 rabbits survived MI operation and were divided into four groups: control group (group B, n = 31), amiodarone group (group C, n = 31), AAP10 group (group D, n = 31) and amiodarone plus AAP10 group (group E, n = 31). The A and B and D groups were treated with saline 2 ml/d, the C and E groups were treated with 2 ml saline containing amiodarone 100 mg×kg(-1)×d(-1). All rabbits were examined by echocardiogram at 12 weeks after operation, then anesthetized by sodium barbital, the left wedge ventricular preparations were cannulated and artery perfused by Tyrode's solution in vitro in the absence (Group A, B and C) and presence of AAP10 (500 nmol/L, Group D and E). The volume electrocardiogram, QT Interval, QRS interval, effective refractory period (ERP), the T-peak to T-end interval (T(p-e)), and ventricular tachycardia episodes induced by programmed stimulation were recorded. The T(p-e)/QT ratio was calculated. After perfusion, gap junctions protein connexin 43 (Cx43) expression was detected by Western blot and immunofluorescence.. The incidence of induced ventricular tachycardia episodes of group A, B, C, D, E was 0, 62.5%, 26.9%, 40.0%, 22.2% respectively. The incidence of induced ventricular tachycardia episodes of group E was less than group B. The T(p-e)/QT ratio in group B, C, D were greater than in group A. The T(p-e)/QT ratio of group E was less than group B. The myocardial Cx43 in the group B was down-regulated and disorganized compared to group A, up-regulated in group C and E compared to group B, up-regulated in group E compared to group D. The Cx43 in the heart of group D and E were well organized than in group B and C.. The artery perfused rabbits wedge preparations with healed myocardial infarction with high incidence of induced ventricular tachycardia episodes are good platform for ventricular arrhythmias research. Combined amiodarone and AAP10 use could decrease the T(p-e)/QT ratio and the incidence of induced ventricular tachycardia episodes. Amiodarone and AAP10 have synergistic effects on upregulating Cx43 and preventing ventricular arrhythmias in this rabbit model of healed myocardial infarction.

Topics: Amiodarone; Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Connexin 43; Male; Myocardial Infarction; Oligopeptides; Rabbits; Treatment Outcome

Topics: Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Fibrinolytic Agents; Male; Oligopeptides; Pulmonary Embolism; Rats

The change in endogenous antiarrhythmic peptide (AAP) levels in serum, heart and kidney from rats under several drug-induced arrhythmias was investigated using a sensitive and specific radioimmunoassay. The extracts from serum, heart and kidney were fractionated by Sephadex G-25 chromatography to obtain a fraction which was found at the same position as that of synthetic AAP. In serum, the immunoreactive (IR)-AAP level increased about threefold under CaCl2-, aconitine- and epinephrine-induced arrhythmias. In heart, the IR-AAP level was doubled by CaCl2, increased 1.4 times by aconitine and decreased by one third by epinephrine. The levels in serum and heart were slightly increased by ADP. The kidney IR-AAP level was not changed under these drug-induced arrhythmias. Considering the previous result that AAP could protect against CaCl2- and aconitine-induced arrhythmias but not against epinephrine-induced arrhythmia, the change in the IR-AAP level in heart coincided with the effect of AAP given to animals under arrhythmia. Quinidine, propranolol and verapamil had no effect on serum IR-AAP level. These results suggested that endogenous AAP in heart worked to suppress certain arrhythmia.

Topics: Aconitine; Adenosine Diphosphate; Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Calcium Chloride; Epinephrine; Oligopeptides; Radioimmunoassay; Rats

Topics: Amino Acid Sequence; Animals; Anti-Arrhythmia Agents; Arrhythmias, Cardiac; Dogs; Drug Evaluation, Preclinical; Hemodynamics; Male; Mice; Oligopeptides; Peptides; Rats; Rats, Inbred Strains