Universität zu Köln

Rittweger, Joern, Debevec, Tadej ORCID: 0000-0001-7053-3978, Frings-Meuthen, Petra, Lau, Patrick, Mittag, Uwe, Ganse, Bergita ORCID: 0000-0002-9512-2910, Ferstl, Philip G., Simpson, Elizabeth J., Macdonald, Ian A., Eiken, Ola and Mekjavic, Igor B. (2016). On the combined effects of normobaric hypoxia and bed rest upon bone and mineral metabolism: Results from the PlanHab study. Bone, 91. S. 130 - 139. NEW YORK: ELSEVIER SCIENCE INC. ISSN 1873-2763

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Abstract

Bone losses are common as a consequence of unloading and also in patients with chronic obstructive pulmonary disease (COPD). Although hypoxia has been implicated as an important factor to drive bone loss, its interaction with unloading remains unresolved. The objective therefore was to assess whether human bone loss caused by unloading could be aggravated by chronic hypoxia. In a cross-over designed study, 14 healthy young men underwent 21-day interventions of bed rest in normoxia (NBR), bed rest in hypoxia (HBR), and hypoxic ambulatory confinement (HAmb). Hypoxic conditions were equivalent to 4000 m altitude. Bone metabolism (NTX, P1NP, sclerostin, DKK1) and phospho-calcic homeostasis (calcium and phosphate serum levels and urinary excretion, PTH) were assessed from regular blood samples and 24-hour urine collections, and tibia and femur bone mineral content was assessed by peripheral quantitative computed tomography (pQCT). Urinary NTX excretion increased (P<0.001) to a similar extent in NBR and HBR (P = 0.69) and P1NP serum levels decreased (P = 0.0035) with likewise no difference between NBR and HBR (P = 0.88). Serum total calcium was increased during bed rest by 0.059 (day D05, SE 0.05 mM) to 0.091 mM (day D21, P < 0.001), with no additional effect by hypoxia during bed rest (P = 0.199). HAmb led, at least temporally, to increased total serum calcium, to reduced serum phosphate, and to reduced phosphate and calcium excretion. In conclusion, hypoxia did not aggravate bed rest-induced bone resorption, but led to changes in phospho-calcic homeostasis likely caused by hyperventilation. Whether hyperventilation could have mitigated the effects of hypoxia in this study remains to be established. (C) 2016 The Authors. Published by Elsevier Inc.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Rittweger, Joern UNSPECIFIED UNSPECIFIED UNSPECIFIED Debevec, Tadej UNSPECIFIED orcid.org/0000-0001-7053-3978 UNSPECIFIED Frings-Meuthen, Petra UNSPECIFIED UNSPECIFIED UNSPECIFIED Lau, Patrick UNSPECIFIED UNSPECIFIED UNSPECIFIED Mittag, Uwe UNSPECIFIED UNSPECIFIED UNSPECIFIED Ganse, Bergita UNSPECIFIED orcid.org/0000-0002-9512-2910 UNSPECIFIED Ferstl, Philip G. UNSPECIFIED UNSPECIFIED UNSPECIFIED Simpson, Elizabeth J. UNSPECIFIED UNSPECIFIED UNSPECIFIED Macdonald, Ian A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Eiken, Ola UNSPECIFIED UNSPECIFIED UNSPECIFIED Mekjavic, Igor B. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-261357
DOI:	10.1016/j.bone.2016.07.013
Journal or Publication Title:	Bone
Volume:	91
Page Range:	S. 130 - 139
Date:	2016
Publisher:	ELSEVIER SCIENCE INC
Place of Publication:	NEW YORK
ISSN:	1873-2763
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language OBSTRUCTIVE SLEEP-APNEA; RENAL STONE FORMATION; OSTEOCLAST FORMATION; PULMONARY-DISEASE; OXYGEN-THERAPY; SPACE-FLIGHT; LOWER LEG; EXERCISE; COPD; SCLEROSTIN Multiple languages Endocrinology & Metabolism Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/26135