title: Antiarrhythmic effects of L-penbutolol and DL-propranolol. Comparison of the effects of these two drugs on conductivity and excitability in canine heart in vivo.
abstract: The effects of l-penbutolol and dl-propranolol on A-V conduction, on excitability of ventricular muscle, and on ventricular tachycardia threshold in acute ischemia were compared, using anesthetized dogs. 1. L-penbutolol (100 microgram/Kg) and dl-propranolol (100 microgram/Kg) prolonged A-V conduction and reduced excitability of ventricular muscle significantly. L-penbutolol less prolonged A-V conduction than dl-propranolol. 2. Both l-penbutolol (50 microgram/Kg) and dl-propranolol (50 microgram/Kg) significantly prevented the lowering of ventricular tachycardia threshold in acute ischemia. These beta-blocking drugs are effective in the treatment of arrhythmia and l-penbutolol could be used safely, because of its weaker inhibition on A-V conduction.
mesh_terms: D000818:Animals; D001145:Arrhythmias, Cardiac / Q000188:drug therapy*; D001283:Atrioventricular Node / Q000187:drug effects; D004285:Dogs; D006329:Heart Conduction System / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006352:Heart Ventricles / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects; D010394:Penbutolol / Q000627:therapeutic use*; D011412:Propanolamines / Q000627:therapeutic use*; D011433:Propranolol / Q000627:therapeutic use*; D013610:Tachycardia / Q000517:prevention & control
chemical_list: D011412:Propanolamines; D010394:Penbutolol; D011433:Propranolol