title: Comparison of the effects of atenolol and practolol on exercise tachycardia in normal subjects.
abstract: The relationship between cumulative doses of practolol and atenolol and resultant decreases in exercise tachycardia has been examined in 4 healthy volunteers. Continuous intravenous infusions of practolol (0.4 mg/kg), atenolol (0.12 mg/kg) and saline were administered between 7 and 12 minutes of bicycle exercise. The mean (+/- S.E.M.) heart rate (HR) at 7 min. for practolol (133 +/- 5.1) and atenolol (132 +/- 2.8) were significantly (p less than .01) reduced to 115 +/- 2.3 and 104 +/- 2.9 beats/min. respectively. The pre-infusion HR in the saline study (132 +/- 1.2) was unchanged (133 +/- 4.6) at 12 min. The relationship between the log cumulative dose of each drug and the per cent fall in HR/min was linear for each subject. The log dose-response curve (mean of 4 subjects) for practolol (y = 9.6x + 18.1) was more horizontal than for atenolol (y = 18.4x + 38.6).
mesh_terms: D000328:Adult; D001262:Atenolol / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005080:Exercise Test; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D008297:Male; D011217:Practolol / Q000494:pharmacology*; D011412:Propanolamines / Q000494:pharmacology*
chemical_list: D011412:Propanolamines; D001262:Atenolol; D011217:Practolol