Adenopituitary hormone response to exercise combined with propranolol infusion in man.

The effect of non-selective beta-blocker propranolol on the changes of plasma GH, prolactin and cortisol level during physical exercise in healthy untrained men has been evaluated. Acute i.v. pretreatment with propranolol resulted in an increased response of plasma GH level to the exercise on a bicycle ergometer. Propranolol significantly potentiated also the response of plasma cortisol level to submaximal exercise. No changes in urinary excretion of free cortisol and 17-OHCS during exercise combined with propranolol infusion as compared to that during exercise alone were observed. The increase of plasma prolactin level after exercise was not altered by propranolol administration. It is suggested that central beta-adrenoreceptors may play an inhibitory role in the control of GH and ACTH secretion during exercise. However, the interaction of propranolol with other central neurotransmitters as well as its peripheral effects, particularly the reduction in physical performance, must also be taken into consideration.