| Spleen contraction during 20 min normobaric hypoxia and 2 min apnea in humans. | |
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MedLine Citation:
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PMID: 20540444 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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INTRODUCTION: Spleen contraction occurs in humans during exercise, apnea, and simulated altitude, resulting in ejection of stored red blood cells into circulation. The mechanisms responsible for initiating the contraction are not fully known: hypoxia is likely involved, but other, unknown factors may also contribute. To reveal the initiating factors, we studied its occurrence in two different situations involving similar reductions in arterial oxygen saturation (SaO2). We hypothesized that similar spleen responses would result if the level of hypoxia is the main factor involved. METHODS: Five female and four male healthy volunteers performed two different trials on separate days: (1) 20 min of normobaric hypoxic breathing (14.2% oxygen); and II) 2 min of apnea after a deep inspiration of air. Both trials started and ended with 10 min of sitting eupneic rest. Spleen diameter was intermittently measured via ultrasonic imaging in three dimensions to calculate volume. SaO2 and heart rate (HR) were recorded continuously with a pulse oximeter. RESULTS: Exposures resulted in similar nadir SaO2: 87% after normobaric hypoxia and 89% after apnea. During normobaric hypoxia, spleen volume was reduced by 16% and during apnea by 34%. HR increased by 7% during normobaric hypoxia, but fell by 25% during apnea. DISCUSSION: Both normobaric hypoxia and apnea induced spleen contraction, but despite similar levels of SaO2 apnea evoked a significantly stronger response, possibly due to hypercapnia, faster desaturation, or the apneic stimulus in itself. Spleen contraction may facilitate adaptation to altitude and to apneic diving by elevating blood gas storage capacity. |
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Authors:
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Angelica Lodin-Sundström; Erika Schagatay |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Aviation, space, and environmental medicine Volume: 81 ISSN: 0095-6562 ISO Abbreviation: Aviat Space Environ Med Publication Date: 2010 Jun |
Date Detail:
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Created Date: 2010-06-14 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 7501714 Medline TA: Aviat Space Environ Med Country: United States |
Other Details:
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Languages: eng Pagination: 545-9 Citation Subset: IM; S |
Affiliation:
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Department of Engineering and Sustainable Development, Mid Sweden University, Ostersund, Sweden. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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