ISSN:
1432-1041
Keywords:
beta-receptor blockade
;
intrinsic sympathomimetic activity
;
exercise haemodynamics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Medicine
Notes:
Summary Beta-adrenergic blockade with intrinsic sympathomimetic activity (ISA) causes less depression of resting and submaximal heart rate (HR) than non-ISA beta-blockers. The effects of these drugs on exercise haemodynamics have not been well studied. We evaluated effects of pindolol, propranolol and placebo during rest and steady-state exercise on cardiac output, oxygen consumption, calf blood flow, HR and blood pressure in 18 healthy subjects. Pindolol 5 mg and propranolol 80 mg given twice daily, reduced maximal exercise HR by 50 and 52 beats·min−1 respectively, confirming similarity of beta1-blockade. Resting cardiac output was unchanged in all three groups after one week of therapy. Cardiac output, measured during steady-state exercise decreased in the propranolol group (18.3 vs 15.6 l·min−1) with no significant changes in pindolol (15.7 vs 16.0 l·min−1) or placebo (18.6 vs 17.3 l·min−1). The rise in cardiac output, from rest to exercise, was similarly attenuated by propranolol but not by pindolol or placebo. Exercise stroke volume increased 12% on pindolol (123–140 cc) and decreased 7% on propranolol (143–133 cc). Neither drug had a detrimental effect on exercise calf blood flow compared to placebo. Thus, unlike propranolol, pindolol with ISA, maintains a normal cardiac output during submaximal exercise.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00561015
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