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Acute and chronic head-down tail suspension diminishes cerebral perfusion in ratsThe purpose of this study was to test the hypothesis that regional brain blood flow and vascular resistance are altered by acute and chronic head-down tail suspension (HDT). Regional cerebral blood flow, arterial pressure, heart rate, and vascular resistance were measured in a group of control rats during normal standing and following 10 min of HDT and in two other groups of rats after 7 and 28 days of HDT. Heart rate was not different among conditions, whereas mean arterial pressure was elevated at 10 min of HDT relative to the other conditions. Total brain blood flow was reduced from that during standing by 48, 24, and 27% following 10 min and 7 and 28 days of HDT, respectively. Regional blood flows to all cerebral tissues and the eyes were reduced with 10 min of HDT and remained lower in the eye, olfactory bulbs, left and right cerebrum, thalamic region, and the midbrain with 7 and 28 days of HDT. Total brain vascular resistance was 116, 44, and 38% greater following 10 min and 7 and 28 days of HDT, respectively, relative to that during control standing. Vascular resistance was elevated in all cerebral regions with 10 min of HDT and remained higher than control levels in most brain regions. These results demonstrate that HDT results in chronic elevations in total and regional cerebral vascular resistance, and this may be the underlying stimulus for the HDT-induced smooth muscle hypertrophy of cerebral resistance arteries.
Document ID
20040088601
Document Type
Reprint (Version printed in journal)
Authors
Wilkerson, M. Keith (College Station TX 77843, United States)
Colleran, Patrick N.
Delp, Michael D.
Date Acquired
August 21, 2013
Publication Date
January 1, 2002
Publication Information
Publication: American journal of physiology. Heart and circulatory physiology
Volume: 282
Issue: 1
ISSN: 0363-6135
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Discipline Cardiopulmonary