Exercise-induced release of pancreatic polypeptide and its inhibition by propranolol: evidence for adrenergic...

Pancreatic polypeptide (PP) has been considered to be predominantly under cholinergic-vagal control and may therefore serve as an indicator of vagal tone. We found similar basal plasma concentrations of PP in athletes with bradycardia and in untrained subjects. We further observed that physical exercise--an adrenergic situation--induces a several-fold rise in PP plasma concentration. Maximal plasma PP levels correlated positively with maximal blood pressure. The exercise-induced rise of PP was completely abolished by propranolol. These findings suggest that stimulation of the adrenergic system releases PP and that therefore plasma PP concentrations cannot be used to determine cholinergic-vagal activity.