Oxygen uptake and plasma catecholamines during submaximal and maximal exercise after long-term beta-receptor blockade

Area of Science:

• Cardiology
• Exercise Physiology
• Pharmacology

Background:

• Beta-receptor antagonists reduce heart rate and cardiac output, potentially impacting exercise performance.
• The effects of beta-1 selective blockers on oxygen transport and physical capacity require investigation, especially during prolonged treatment.

Purpose of the Study:

• To evaluate the impact of short-term (4-week) and long-term (15-month) acebutolol treatment on oxygen uptake and catecholamine levels during exercise.
• To determine if acebutolol affects maximal workload and exercise capacity in hypertensive men.

Main Methods:

• Eight male patients with WHO stage 1 hypertension received 500 mg of acebutolol daily.
• Measurements included oxygen uptake, ventilation, plasma catecholamines (noradrenaline, adrenaline, dopamine), and maximal workload during submaximal and maximal exercise tests.

Main Results:

• Short-term acebutolol treatment showed a trend towards reduced maximal oxygen uptake and workload, but increased oxygen pulse.
• Long-term (15-month) treatment resulted in maximal oxygen uptake similar to baseline, with a tendency for higher maximal workload and significantly increased plasma noradrenaline and adrenaline.
• Heart rate was significantly reduced in both short-term and long-term treatment groups.

Conclusions:

• Beta-1 selective receptor blockers like acebutolol do not negatively affect maximal oxygen uptake and maximal work capacity after long-term administration.
• Acebutolol may be a suitable option for hypertensive patients participating in preventive and rehabilitative exercise programs.