title: Head-up tilt and lower body suction: comparison of hormone responses in healthy men.
abstract: The purpose of this study was to compare, in the same subjects, hormonal responses to 30-min head-up tilt (HUT) and lower body suction (LBNP) of different intensity (24 degrees and 70 degrees, and 15 and 35 mm Hg, respectively). Basal pooled individual data from -10 min (n = 32) were within normal reference limits: norepinephrine (NE) averaged 318 +/- 23 pg/ml; epinephrine, 34.0 +/- 5.5 pg/ml; plasma renin activity (PRA), 0.72 +/- 0.08 ng ATII/ml/h; aldosterone, 164 +/- 20 pg/ml; atrial natriuretic peptide (ANP), 29.9 +/- 2.0 pg/ml; cGMP, 6.29 +/- 0.59 mmol/l; cortisol, 95.7 +/- 5.8 ng/ml; and ACTH, 50.3 +/- 2.6 pg/ml. The low-level stimuli failed to induce consistent changes in hormone levels. From the onset of the stimulus (minute 0) to its termination (minute 30), norepinephrine (NE) increased by 101% with LBNP-35, and by 70% with HUT70, respectively. The NE increase with LBNP-35 was higher (p < 0.05) than with HUT70. Epinephrine rose with HUT70 (by 162%) only. PRA increased by 157% with LBNP-35, and by 119% with HUT70, respectively; these responses were not significantly different. Aldosterone rose equally (by 85 and 89%) with LBNP-35 and HUT70 but not with the low-level stimuli. No consistent changes were observed in ANP, c-GMP or ACTH concentrations. Cortisol values fell during the LBNP and HUT24 situations but rose transiently after HUT70. We conclude that the hormones investigated respond differently to head-up posture and lower body suction and in a specific manner. Greater effects of high-level stimuli (HUT70, LBNP-35) were noted as compared to low-level stimuli (HUT24, LBNP-15). The application of combined sets of models stimulating the cardiovascular system may aid in the analysis of responses of hormonal systems in man.
authors.affiliation: Department of Physiology, School of Medicine, Karl-Franzens-University, Graz, Austria.
authors.forename: H G
authors.initials: HG
authors.lastname: Hinghofer-Szalkay
authors.forename: M
authors.initials: M
authors.lastname: Vigas
authors.forename: G
authors.initials: G
authors.lastname: Sauseng-Fellegger
authors.forename: E M
authors.initials: EM
authors.lastname: König
authors.forename: B
authors.initials: B
authors.lastname: Lichardus
authors.forename: D
authors.initials: D
authors.lastname: Jezová
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006728:Hormones / Q000097:blood*; D006801:Humans; D008150:Lower Body Negative Pressure; D008297:Male; D011187:Posture / Q000502:physiology*; D013997:Time Factors
chemical_list: D006728:Hormones