title: Plasma Met-enkephalin and catecholamine responses to intense exercise in humans.
abstract: Native and cryptic Met-enkephalin and catecholamines are coreleased in response to stress. However, it is not known whether Met-enkephalin and catecholamines exhibit concurrent temporal relationships in response to exercise. The purpose of this investigation was to examine the corelease of catecholamines and Met-enkephalin in endurance-trained (n = 6) and untrained (n = 6) male subjects during a 6-min bout of exercise: 4 min at 70% of maximal O2 uptake (VO2max) followed by 2 min at 120% VO2max. Peak catecholamine levels were found at 1 min of recovery. In trained subjects, native Met-enkephalin peaked during exercise at 70% VO2max, declined during exercise at 120% VO2max, and returned to basal levels by 1 min of recovery. In the untrained subjects, native Met-enkephalin peaked at 120% VO2max (6 min) and returned to baseline by 5 min of recovery. In both groups, cryptic Met-enkephalin peaked at 70% VO2max and returned to basal levels during exercise at 120% VO2max. These data demonstrate that during exercise there is a temporal dissociation in plasma levels of Met-enkephalin and catecholamines.
authors.affiliation: Department of Medicine, University of Kentucky, Lexington.
authors.forename: J B
authors.initials: JB
authors.lastname: Boone
authors.forename: T
authors.initials: T
authors.lastname: Sherraden
authors.forename: K
authors.initials: K
authors.lastname: Pierzchala
authors.forename: R
authors.initials: R
authors.lastname: Berger
authors.forename: G R
authors.initials: GR
authors.lastname: Van Loon
mesh_terms: D000328:Adult; D002395:Catecholamines / Q000097:blood*; D004744:Enkephalin, Methionine / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training
chemical_list: D002395:Catecholamines; D004744:Enkephalin, Methionine