Effects of Atropine and Propranolol on the Oxygen Transport System during Exercise in Man

Abstract

Healthy subjects performed submaximal and maximal bicycle exercise under 1) control conditions, and after injection of 2) atropine (2.0–2.5 mg i.v.), 3) propranolol (10 mg i.v.), 4) both these drugs. Lowest heart rate was noticed after propranolol and at any level of exercise the average heart rate was about 40 beats/min lower than after injection of atropine. The maximal oxygen uptake was, however, unchanged except after both drugs (6 % reduction). Maximal work time and cardiac output were significantly reduced after injection of propranolol. Thus, a remarkably efficient arterial oxygen transport can be maintained during heavy exercise despite a wide variation in heart rate.

Key Words:

• Atropine
• autonomic nervous activity
• blood lactates
• blood pressure
• cardiac output
• heart rate
• maximal work
• oxygen uptake
• propranolol
• stroke volume