Changes in serum potassium concentration with exercise in Hereford calves: effects of adrenalectomy

1. Serum potassium concentration [K+] was measured pre- and postadrenalectomy in three Hereford steer calves before, during and following 3.5 min exercise at their maximal speed capability. 2. Both before and after adrenalectomy, serum [K+] increased an average of 2.4 mEq.1(-1) during exercise and was at control levels 10 min postexercise. 3. Hormones from neither the adrenal cortex nor the adrenal medulla influence serum [K+] dynamics during acute exercise.