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

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 mumol X 1(-1). The corresponding rise after propranolol 40 mg was 56 mumol X 1(-1) (p less than 0.01). All three doses of propranolol produced similar effects on plasma ammonia and exercise heart rates.