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The Gravity of Giraffe PhysiologyBy virtue of its tallness and terrestrial environment, the giraffe is a uniquely sensitive African animal to investigate tissue adaptations to gravitational stress. One decade ago, we studied transcapillary fluid balance and local tissue adaptations to high cardiovascular and musculoskeletal loads in adult and fetal giraffes. Previous studies by Goetz, Pattersson, Van Citters, Warren and their colleagues revealed that arterial pressure near the giraffe heart is about twice that in humans, to provide more normal blood pressure and perfusion to the brain. Another important question is how giraffes avoid pooling of blood and tissue fluid (edema) in dependent tissue of the extremities. As monitored by radiotelemetry, the blood and tissue fluid pressures that govern transcapillary exchange vary greatly with exercise. These pressures, combined with a tight skin layer, move fluid upward against gravity. Other mechanisms that prevent edema include precapillary vasoconstriction and low permeability of capillaries to plasma proteins. Other anatomical adaptations in dependent tissues of giraffes represent developmental adjustments to high and variable gravitational forces. These include vascular wall hypertrophy, thickened capillary basement membrane and other connective tissue adaptations. Our results in giraffe suggest avenues of future gravitational research in other animals including humans.
Document ID
20020042320
Document Type
Conference Paper
Authors
Hargens, Alan R. (NASA Ames Research Center Moffett Field, CA United States)
Holton, Emily M.
Date Acquired
August 20, 2013
Publication Date
January 1, 1997
Subject Category
Life Sciences (General)
Meeting Information
International Conference on Comparative Physiology and Biochemistry(Skukuza)
Funding Number(s)
PROJECT: RTOP 199-26-12-34
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.