title: Class III action of beta-blocking agents.
abstract: We have studied the effect of the intravenous administration of the following drugs on ventricular refractoriness in 35 experiments in open chested beagle dogs: atenolol 0.2 mg X kg-1; nadolol 0.05 mg X kg-1; oxprenolol 0.2 mg X kg-1; pindolol 0.04 mg X kg-1; propranolol 0.2 mg X kg-1; sotalol 0.6 mg X kg-1 and timolol 0.1 mg X kg-1. The animals were anaesthetised with chloralose and urethane. Measurements were made of left ventricular epicardial monophasic action potentials (MAP) (n = 35) and the left ventricular paced evoked response (PER) (n = 25) at a fixed paced cycle length of between 220 and 310 ms. The animals were initially beta-blocked with iv pindolol or propranolol and the drug under study then administered iv 10 min later. The results were as follows: (control and post drug administration) MAP: nadolol 151 +/- 12 SD to 172 +/- 13 SD (p less than 0.001); oxprenolol 153 +/- 21 to 178 +/- 20 (p less than 0.001); sotalol 153 +/- 19 to 176 +/- 20 (p less than 0.001); atenolol 152 +/- 25 to 153 +/- 23 (NS); pindolol 149 +/- 11 to 152 +/- 10 (NS); propranolol 152 +/- 26 to 155 +/- 26 (NS); timolol 144 +/- 23 to 144 +/- 21 (NS). PER: nadolol 172 +/- 14 to 190 +/- 20 (p less than 0.001); oxprenolol 164 +/- 16 to 188 +/- 15 (p less than 0.001); propranolol 166 +/- 22 to 173 +/- 18 (NS).(ABSTRACT TRUNCATED AT 250 WORDS)
mesh_terms: D000200:Action Potentials / Q000187:drug effects; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D001262:Atenolol / Q000494:pharmacology; D002304:Cardiac Pacing, Artificial; D004285:Dogs; D004562:Electrocardiography; D005260:Female; D006321:Heart / Q000187:drug effects* / Q000502:physiology; D006352:Heart Ventricles / Q000187:drug effects; D008297:Male; D009248:Nadolol; D010096:Oxprenolol / Q000494:pharmacology; D010869:Pindolol / Q000494:pharmacology; D011412:Propanolamines / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D013015:Sotalol / Q000494:pharmacology; D013999:Timolol / Q000494:pharmacology
chemical_list: D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D009248:Nadolol; D001262:Atenolol; D010096:Oxprenolol; D013999:Timolol; D011433:Propranolol; D013015:Sotalol; D010869:Pindolol