Journal of Applied Physiology, Vol 71, Issue 6 2469-2475, Copyright © 1991 by American Physiological Society

ARTICLES

Transcapillary fluid shifts in tissues of the head and neck during and after simulated microgravity

S. E. Parazynski, A. R. Hargens, B. Tucker, M. Aratow, J. Styf and A. Crenshaw
Life Sciences Division, National Aeronautics and Space Administration-Ames Research Center, Moffett Field, California 94035-1000.

To understand the mechanism, magnitude, and time course of facial puffiness that occurs in microgravity, seven male subjects were tilted 6 degrees head-down for 8 h, and all four Starling transcapillary pressures were directly measured before, during, and after tilt. Head-down tilt (HDT) caused facial edema and a significant elevation of microvascular pressures measured in the lower lip: capillary pressures increased from 27.7 +/- 1.5 mmHg (mean +/- SE) pre-HDT to 33.9 +/- 1.7 mmHg by the end of tilt. Subcutaneous and intramuscular interstitial fluid pressures in the neck also increased as a result of HDT, whereas interstitial fluid colloid osmotic pressures remained unchanged. Plasma colloid osmotic pressure dropped significantly by 4 h of HDT (21.5 +/- 1.5 mmHg pre-HDT to 18.2 +/- 1.9 mmHg), suggesting a transition from fluid filtration to absorption in capillary beds between the heart and feet during HDT. After 4 h of seated recovery from HDT, microvascular pressures in the lip (capillary and venule pressures) remained significantly elevated by 5-8 mmHg above baseline values. During HDT, urine output was 126.5 ml/h compared with 46.7 ml/h during the control baseline period. These results suggest that facial edema resulting from HDT is caused primarily by elevated capillary pressures and decreased plasma colloid osmotic pressures. The negativity of interstitial fluid pressures above heart level also has implications for maintenance of tissue fluid balance in upright posture.

This article has been cited by other articles:

				A. A. Gashev, M. D. Delp, and D. C. Zawieja Inhibition of active lymph pump by simulated microgravity in rats Am J Physiol Heart Circ Physiol, June 1, 2006; 290(6): H2295 - H2308. [Abstract] [Full Text] [PDF]

				J. C. Barbato, Q.-Q. Huang, M. M. Hossain, M. Bond, and J.-P. Jin Proteolytic N-terminal Truncation of Cardiac Troponin I Enhances Ventricular Diastolic Function J. Biol. Chem., February 25, 2005; 280(8): 6602 - 6609. [Abstract] [Full Text] [PDF]

				T. M. Gotoh, N. Fujiki, K. Tanaka, T. Matsuda, S. Gao, and H. Morita Acute hemodynamic responses in the head during microgravity induced by free drop in anesthetized rats Am J Physiol Regulatory Integrative Comp Physiol, June 1, 2004; 286(6): R1063 - R1068. [Abstract] [Full Text] [PDF]

				D. E. Watenpaugh Fluid volume control during short-term space flight and implications for human performance J. Exp. Biol., March 11, 2002; 204(18): 3209 - 3215. [Abstract] [Full Text] [PDF]

				J. R. Styf, K. Hutchinson, S. G. Carlsson, and A. R. Hargens Depression, Mood State, and Back Pain During Microgravity Simulated by Bed Rest Psychosom Med, November 1, 2001; 63(6): 862 - 864. [Abstract] [Full Text] [PDF]

				M. K. Wilkerson, J. Muller-Delp, P. N. Colleran, and M. D. Delp Effects of hindlimb unloading on rat cerebral, splenic, and mesenteric resistance artery morphology J Appl Physiol, December 1, 1999; 87(6): 2115 - 2121. [Abstract] [Full Text] [PDF]

				A. Haskell, E. R. Nadel, N. S. Stachenfeld, K. Nagashima, and G. W. Mack Transcapillary escape rate of albumin in humans during exercise-induced hypervolemia J Appl Physiol, August 1, 1997; 83(2): 407 - 413. [Abstract] [Full Text] [PDF]