Résumé : Exercise stimulates the release of the atrial natriuretic factor (ANF).1-3 The principal determinant of ANF release is atrial distension,4 although adrenergic stimulation has also been implicated in the direct release of ANF.5,6 Both of these mechanisms could account for the release of ANF during exercise. To elucidate the relative roles of these mechanisms, we determined the plasma ANF concentrations and cardiac volumes during exercise before and after β-adrenergic blockade with propranolol. © 1989.