title: Free plasma catecholamine levels in healthy subjects: a basal and dynamic study. The influence of age.
abstract: We studied the levels of free plasma noradrenaline (norepinephrine, NE), adrenaline (epinephrine, E), and dopamine (DA) in 143 normal subjects, either basally or, in a part of them, in response to four tests stimulating the sympathoadrenomedullary activity: the tilt-table test (TTT), the cold-pressor test (CPT), the mental-arithmetic test (MAT), and the insulin tolerance test (ITT). In both cases we evaluated the influence of age, which is considered the main physiological variable affecting the peripheral sympathetic activity. A normal distribution of values was observed, in the basal study, only for NE, while E and particularly, DA levels were distributed in an non-homogeneous fashion; a direct correlation was observed between age of subjects and NE levels, while neither E, nor DA levels showed any correlation with the aging process; sex did not influence any of the catecholamines. In the dynamic study, CPT, ITT and, above all, TTT elicited a significant rise in NE levels, while the E release was greatly stimulated by the insulin-induced hypoglycaemia. Neither NE, nor E levels rose after the MAT stimulation. Also in this case, the elderly showed an increased noradrenergic responsiveness when compared with the young subjects, confirming the existence of an 'up-regulation' of the peripheral sympathetic tone in old people.
authors.affiliation: Neurochronobiology Unit, University of Pavia, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Blandini
authors.forename: E
authors.initials: E
authors.lastname: Martignoni
authors.forename: G V
authors.initials: GV
authors.lastname: Melzi d'Eril
authors.forename: L
authors.initials: L
authors.lastname: Biasio
authors.forename: G
authors.initials: G
authors.lastname: Sances
authors.forename: C
authors.initials: C
authors.lastname: Lucarelli
authors.forename: V
authors.initials: V
authors.lastname: Rizzo
authors.forename: A
authors.initials: A
authors.lastname: Costa
authors.forename: G
authors.initials: G
authors.lastname: Nappi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood*; D001481:Basal Metabolism / Q000502:physiology*; D002395:Catecholamines / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D013312:Stress, Physiological / Q000097:blood*; D013315:Stress, Psychological / Q000097:blood*
chemical_list: D002395:Catecholamines