EFFECTS OF BETA-ADRENOCEPTOR-BLOCKADE ON STRESS-INDUCED ADRENOCORTICOTROPIN RELEASE IN HUMANS

We investigated the mechanisms of stress-induced alterations in adreno corticotrophin (ACTH) release. Tandem parachutists received either a p lacebo or the beta-adrenoceptor antagonist propranolol prior to a firs t time parachute jump. Blood samples were drawn 4 h before, immediatel y after, and 1 h after the jump. Cortisol and catecholamine concentrat ions displayed a significant stress-induced increase in both groups. T he ACTH plasma concentrations significantly increased in the placebo a nd the propranolol group, with significantly more pronounced changes i n the propranolol-treated subjects compared to the placebo group. Thes e data demonstrated a stress-induced increase of ACTH plasma concentra tions in humans that was enhanced by beta-blockade.