Effects on atrio-ventricular conduction of propranolol, pindolol and carteolol in the dog heart in situ as assessed by automated devices.
In open-chest dogs the heart rate was controlled at 150 beats/min and drugs were given intravenously. Propranolol (30 microgram/kg--1 mg/kg) prolonged the atrioventricular (A-V) conduction time and functional refractory period of the A-V conduction system (FRP) by blockade of the existing tone of the sympathetic nerves to the heart. The prolongation of the two parameters by the non-specific depressant action of propranolol was evident only at 3 mg/kg. Propranolol (3--30 microgram/kg) shortened the A-V conduction time in the heart deprived of the vagal and sympathetic tone, suggesting some sort of sympathomimetic effect. Pindolol in a wide range of doses (0.3--300 microgram/kg) exerted virtually no effect on the A-V conduction time and FRP, and its non-specific depressant action was apparent only at 3 mg/kg. Carteolol slightly prolonged the A-V conduction time and FRP only in low doses (1--10 microgram/kg), and in high doses (30 microgram/kg--1 mg/kg) it shortened the two parameters, reflecting its predominant sympathomimetic action.
D000818:Animals; D002354:Carteolol / Q000494:pharmacology*; D003864:Depression, Chemical; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D006329:Heart Conduction System / Q000187:drug effects*; D008297:Male; D008722:Methods; D010869:Pindolol / Q000494:pharmacology*; D011412:Propanolamines / Q000494:pharmacology*; D011433:Propranolol / Q000494:pharmacology*
D011412:Propanolamines; D002354:Carteolol; D011433:Propranolol; D010869:Pindolol