1 Intravenous propranolol and practolol both reduced resting supine heart rate in patients with hyperthyroidism. Propranolol produced a significantly greater reduction than practolol, which did not have a dose-dependent effect. 2 The effect of these drugs on resting heart rate was much less than their effect on the tachycardias produced both by severe exercise and by standing upright in hyperthyroid patients. Propranolol again produced a significantly greater reduction than practolol in each situation, but practolol did have a dose dependent effect on exercise heart rate. 3 The percentage reduction of standing tachycardia produced by the two drugs appeared to parallel closely the reduction in exercise tachycardia. 4 It is concluded that a simple and convenient way of assessing the activity of β-adrenoceptor blocking drugs in hyperthyroid patients would be to measure their effect on the tachycardia induced by standing. Their effect on resting heart rate should not be used. 5 Practolol may be useful in the management of hyperthyroidism in patients in whom propranolol and similar non-selective β-adrenoceptor blocking drugs are contraindicated.
Comparison of the effects of I.C.I. 50172 and propranolol on the cardiovascular responses to adrenaline, isoprenaline and exercise
Control of heart rate by the autonomic nervous system. Studies in man on the interrelation between baroreceptor mechanisms and exercise
Effects of S-adenosyl-methionine on plasma norepinephrine, blood pressure, and heart rate in healthy volunteers
The effect of cimetidine on the relative cardioselectivity of atenolol and metoprolol in asthmatic patients
Cardiovascular effects of single oral doses of the new beta-adrenoceptor blocking agents betaxolol (SL 75212) in healthy volunteers
Adrenergic Receptors: Trafficking
Adrenergic receptor trafficking is an active physiological process where adrenergic receptors are relocated from one region of the cell to another or from one type of cell to another. Discover the latest research on adrenergic receptor trafficking here.