Cardiovascular and humoral readjustment after different levels of head-up tilt in humans

Z. László, A. Rössler, H. G. Hinghofer-Szalkay

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

Purpose: To get a more complete picture of cardiovascular regulation after postural changes, this investigation directly monitored volume-related, hemodynamic, and endocrine variables during and after 30 min of passive head-up tilt (HUT) of various degrees. It was hypothesized that the return of variables to pre-tilt control level is of system-specific duration and different from what is found after lower body negative pressure (LBNP). Design: We tested 7 persons on 5 different days using, in random order, no (HUT0) or different intensity (12°, 30°, 53°, and 70°) of passive orthostasis (HUT12, HUT30, HUT53, HUT70). Data were collected before (supine), during, and after (supine) HUT and compared with synchronous data from HUT0. Results: There was graded alteration with the sine of tilt angle for all hormones and directly volume-related variables. The effects of HUT70 were of the same magnitude as previously documented by others. After HUT, hemodynamic variables and catecholamines returned to control levels most rapidly. Heart rate depression, as observed in a companion LBNP study in the same subjects, did not occur. Vasopressin, PRA, plasma volume and Z0 returned to nominal values more slowly. Plasma aldosterone was still elevated 50 min after reassuming supine posture. Conclusion: Besides specific dose-responses within hemodynamic, volume-dependent, and hormonal variables after orthostatic loading of different degree, the return to control levels after HUT occurs with distinctly different time-courses, which are not identical with those seen after LBNP-simulated orthostasis.

Original languageEnglish
Pages (from-to)193-201
Number of pages9
JournalAviation Space and Environmental Medicine
Volume72
Issue number3
Publication statusPublished - Mar 21 2001

Keywords

  • Aldosterone
  • Blood volume
  • Catecholamines
  • Hemodynamics
  • Orthostatic challenge
  • Renin
  • Supine posture
  • Thoracic bioimpedance
  • Vasopressin

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health

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