Ades P A, Wolfel E E, Hiatt W R, Fee C, Rolfs R, Brammell H L, Horwitz L D
Division of Cardiology and Internal Medicine, University of Colorado Health Sciences Center, Denver.
Eur J Clin Pharmacol. 1989;36(1):5-10. doi: 10.1007/BF00561015.
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 beta 1-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 16.01.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.
具有内在拟交感活性（ISA）的β-肾上腺素能阻滞剂对静息心率和次最大心率（HR）的抑制作用比不具有ISA的β-阻滞剂小。这些药物对运动血流动力学的影响尚未得到充分研究。我们评估了18名健康受试者在静息和稳态运动期间，吲哚洛尔、普萘洛尔和安慰剂对心输出量、耗氧量、小腿血流量、心率和血压的影响。每天两次给予5毫克吲哚洛尔和80毫克普萘洛尔，分别使最大运动心率降低50次/分钟和52次/分钟，证实了β1阻断作用的相似性。治疗一周后，所有三组的静息心输出量均未改变。在稳态运动期间测量的心输出量，普萘洛尔组降低（18.3对15.6升/分钟），吲哚洛尔组（15.7对16.0升/分钟）和安慰剂组（18.6对17.3升/分钟）无显著变化。从静息到运动的心输出量增加，普萘洛尔使其同样减弱，但吲哚洛尔和安慰剂则不然。运动每搏输出量在吲哚洛尔组增加12%（123 - 140立方厘米），在普萘洛尔组降低7%（143 - 133立方厘米）。与安慰剂相比，两种药物对运动时小腿血流量均无有害影响。因此，与普萘洛尔不同，具有ISA的吲哚洛尔在次最大运动期间维持正常的心输出量。
