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Baroreflex impairment during rapid posture changes at rest and exercise after 120 days of bed rest.
Karolinska Institutet.
Karolinska Institutet.
KTH, School of Technology and Health (STH), Basic Science and Biomedicine, Environmental Physiology. Karolinska Institutet.ORCID iD: 0000-0001-6361-8965
2006 (English)In: European Journal of Applied Physiology, ISSN 1439-6319, E-ISSN 1439-6327, Vol. 96, no 1, 37-45 p.Article in journal (Refereed) Published
Abstract [en]

Orthostatic intolerance is common after space flight and head-down tilt (HDT) bed rest. We hypothesized that HDT-induced impairments of arterial blood pressure (AP) control would be more marked during exercise and that recovery of baroreflex function after very long-term HDT would be delayed. Six subjects were studied before (BDC) during (day 60, D60; D113) and after (recovery day 0, R0; R3; R15) 120 days of HDT. Supine resting subjects were exposed to repeated 1 min passive tilts to upright at 3-min interval. During 50 W steady-state exercise corresponding tilt had a 2-min duration at 4-min interval. The amplitudes of the tilt-induced transient beat-by-beat deviations in AP and rate (HR) were determined during the gravity transients. At rest these deviations did not change over time, but during exercise the total peak-to-nadir range of deviations in systolic AP (SAP) at up-tilt and down-tilt increased to 168+/-16% (mean+/-SEM) of BDC at D113 with no clear recovery upto and including R15. Counter-regulatory HR responses were not increased proportionally and especially not tachycardic responses to up-tilt, resulting in a reduction of baroreflex sensitivity (deltaRR-interval/deltaSAP) by 55+/-9% of BDC at D113 with no recovery upto and including R15. We conclude that prolonged bed rest cause long-lasting impairments in AP control and baroreflex function in exercising humans.

Place, publisher, year, edition, pages
2006. Vol. 96, no 1, 37-45 p.
Keyword [en]
simulated microgravity, head down tilt; tilt, arterial blood pressure
National Category
URN: urn:nbn:se:kth:diva-123228DOI: 10.1007/s00421-005-0062-zISI: 000233722300006ScopusID: 2-s2.0-29544435097OAI: diva2:625528

QC 20130610

Available from: 2013-06-05 Created: 2013-06-05 Last updated: 2016-04-27Bibliographically approved

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