EFFECTS OF ANTIARRHYTHMIC DRUGS ON EXCITABILITY OF RABBIT CARDIAC VENTRICLE

• Published in: Journal of The Showa Medical Association Vol. 47; no. 3; pp. 405 - 413
• Main Author: IZUMO, Kazuhide
• Format: Journal Article
• Language: Japanese
• Published: The Showa University Society 1987
• ISSN: 0037-4342; 2185-0976
• DOI: 10.14930/jsma1939.47.405

Effects of antiarrhythmic drugs on excitability of rabbit cardiac ventricle were in situ studied when stimulated by anodal current less than mlA. Drugs used were: lidocaine (L, 2.0mg/kg), procaineamide (Pa, 8.0mg/kg) and dysopiramide (Dys, 1.5mg/kg) . The calcium antagonists, verapamil (V, 0.25mg/kg) and diltiazem (Dil, 0.35mg/kg), were also evaluated the plasma concentrations of the drugs were kept within their ranges of clnical use. End-diastolic threshold (EDT), effective refractory period (ERP), supernormal period (S-P) and dip phenomena (DIP) were measured from Strength-lnterval curves before, immediately and 10 minutes after infusion of drugs. L increased EDT, prolonged ERP, and made S-P and DIP disappear. Pa and Dys showed increased EDT and prolonged ERP, as similar L, but maintained S-P and DIP. V and Dil had no effect on cardiac excitability in the clinical plasma concentrations used.