Catecholamine Modulation of Rapid Potassium Shifts during Exercise

Plasma potassium rises during muscular exercise and falls rapidly when exercise is stopped. Since the sympathoadrenal system is stimulated with exertion and both α- and β-adrenergic agonists affect internal potassium homeostasis, we studied the influence of catecholamines on potassium shifts during and after exercise. Six healthy subjects were given maximal exercise stress tests under three conditions: with no medication (control), during β-blockade with propranolol, and during α-blockade with phentolamine. Compared with a peak rise in plasma potassium of 1.23±0.27 mmol per liter (mean ±S.E.M.) during the control study, propranolol caused a rise of 1.89±0.35 (P