The effect of propranolol on the rise in plasma ammonia during modest exercise

Summary Changes in plasma ammonia in response to exercise with and without pretreatment with propranolol have been studied. A standardised submaximal treadmill exercise test was used to assess the effects of placebo or propranolol 40 mg, 80 mg, or 160 mg twice daily given in random order for 3 days, the last dose being taken 90 min before exercise. After placebo the mean incremental rise in plasma ammonia in response to exercise was 16 µmol·l^–1. The corresponding rise after propranolol 40mg was 56 µmol·l^–1 (p<0.01). All three doses of propranolol produced similar effects on plasma ammonia and exercise heart rates.