Role of sympathetic excitation in generating arrhythmias in early and late phases of ectopic responses after coronary arterial occlusion in dog heart.
The three phases of arrhythmias that develop within specific durations of occlusion of a coronary artery of the dog have been reviewed and characterized. The intravenous administration of practolol as described has virtually prevented the occurrence of arrhythmic activity during the first 7-8 hr after occlusion and kept the frequency at a much reduced level as compared with controls through 10 or 11 hr, but not appreciably longer. This means that first and second phase arrhythmias were almost abolished, and development of third phase ventricular tachycardia was significantly retarded, but not prevented. It is concluded that sympathetic stimulation is an important component in the effective excitation of ectopic activity during the first and second phases, but contributed no more than a minor component to the fully developed third phase activity.
D000818:Animals; D001145:Arrhythmias, Cardiac / Q000209:etiology / Q000503:physiopathology* / Q000517:prevention & control; D003326:Coronary Circulation; D003331:Coronary Vessels; D004195:Disease Models, Animal; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D008026:Ligation; D011217:Practolol / Q000627:therapeutic use; D012039:Regional Blood Flow; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D013997:Time Factors
D011217:Practolol