Universität zu Köln

Kramer, Larry A., Hasan, Khader M., Sargsyan, Ashot E., Marshall-Goebel, Karina ORCID: 0000-0002-5240-7625, Rittweger, Joern, Donoviel, Dorit, Higashi, Saki, Mwangi, Benson, Gerlach, Darius A. and Bershad, Eric M. (2017). Quantitative MRI volumetry, diffusivity, cerebrovascular flow, and cranial hydrodynamics during head-down tilt and hypercapnia: the SPACECOT study. J. Appl. Physiol., 122 (5). S. 1155 - 1167. BETHESDA: AMER PHYSIOLOGICAL SOC. ISSN 1522-1601

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Abstract

To improve the pathophysiological understanding of visual changes observed in astronauts, we aimed to use quantitative MRI to measure anatomic and physiological responses during a ground-based spaceflight analog (head-down tilt, HDT) combined with increased ambient carbon dioxide (CO2). Six healthy, male subjects participated in the double-blinded, randomized crossover design study with two conditions: 26.5 h of -12 degrees HDT with ambient air and with 0.5% CO2, both followed by 2.5-h exposure to 3% CO2. Volume and mean diffusivity quantification of the lateral ventricle and phase-contrast flow sequences of the internal carotid arteries and cerebral aqueduct were acquired at 3 T. Compared with supine baseline, HDT (ambient air) resulted in an increase in lateral ventricular volume (P = 0.03). Cerebral blood flow, however, decreased with HDT in the presence of either ambient air or 0.5% CO2 (P = 0.002 and P = 0.01, respectively); this was partially reversed by acute 3% CO2 exposure. Following HDT (ambient air), exposure to 3% CO2 increased aqueductal cerebral spinal fluid velocity amplitude (P = 0.01) and lateral ventricle cerebrospinal fluid (CSF) mean diffusivity (P = 0.001). We concluded that HDT causes alterations in cranial anatomy and physiology that are associated with decreased craniospinal compliance. Brief exposure to 3% CO2 augments CSF pulsatility within the cerebral aqueduct and lateral ventricles. NEW & NOTEWORTHY Head-down tilt causes increased lateral ventricular volume and decreased cerebrovascular flow after 26.5 h. Additional short exposure to 3% ambient carbon dioxide levels causes increased cerebrovascular flow associated with increased cerebrospinal fluid pulsatility at the cerebral aqueduct. Head-down tilt with chronically elevated 0.5% ambient carbon dioxide and acutely elevated 3% ambient carbon dioxide causes increased mean diffusivity of cerebral spinal fluid within the lateral ventricles.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Kramer, Larry A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hasan, Khader M. UNSPECIFIED UNSPECIFIED UNSPECIFIED Sargsyan, Ashot E. UNSPECIFIED UNSPECIFIED UNSPECIFIED Marshall-Goebel, Karina UNSPECIFIED orcid.org/0000-0002-5240-7625 UNSPECIFIED Rittweger, Joern UNSPECIFIED UNSPECIFIED UNSPECIFIED Donoviel, Dorit UNSPECIFIED UNSPECIFIED UNSPECIFIED Higashi, Saki UNSPECIFIED UNSPECIFIED UNSPECIFIED Mwangi, Benson UNSPECIFIED UNSPECIFIED UNSPECIFIED Gerlach, Darius A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Bershad, Eric M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-232104
DOI:	10.1152/japplphysiol.00887.2016
Journal or Publication Title:	J. Appl. Physiol.
Volume:	122
Number:	5
Page Range:	S. 1155 - 1167
Date:	2017
Publisher:	AMER PHYSIOLOGICAL SOC
Place of Publication:	BETHESDA
ISSN:	1522-1601
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language NORMAL-PRESSURE HYDROCEPHALUS; CEREBRAL-BLOOD-FLOW; OPTIC DISC EDEMA; INTRACRANIAL-PRESSURE; CEREBROSPINAL-FLUID; CHOROID-PLEXUS; HUMAN-BRAIN; SIMULATED MICROGRAVITY; VENOUS-PRESSURE; ISCHEMIC-STROKE Multiple languages Physiology; Sport Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23210