|
|
||||||||
AJP - Heart and Circulatory Physiology, Vol 263, Issue 4 1270-H1275, Copyright © 1992 by American Physiological Society
ARTICLES |
H. Hinghofer-Szalkay, E. M. Konig, G. Sauseng-Fellegger and C. Zambo-Polz
Department of Physiology, Karl-Franzens-University, Graz, Austria.
We recorded blood and plasma mass density and hematocrit of antecubital venous blood in 12 subjects in the supine position before, during, and after 20-40 min of lower body subatmospheric pressure (LBNP) of -35 mmHg. Mass density values decreased during the first minutes of LBNP, indicating a transient 2.8% blood volume gain before they rose as expected. After LBNP, a pronounced further density increase, indicating a further 1.5% hemoconcentration, preceded the return toward control. This pattern suggests reflex-driven transient filtration effects. Computed mass density of fluid exchanged between blood and extravascular space was 1,007.2 +/- 4.4 milligrams (37.0 degrees C); mass density of erythrocytes remained unaltered. We conclude that sudden unloading of central pressure receptors with LBNP causes microvascular fluid gain preceding fluid loss (hemoconcentration) during LBNP, and receptor loading after LBNP additionally causes fluid loss preceding inward filtration (hemodilution) during recovery. These effects can be quantified with high-precision blood and plasma mass densitometry performed by the mechanical oscillator technique.
This article has been cited by other articles:
![]() |
S. Masuki, J. H. Eisenach, C. P. Johnson, N. M. Dietz, L. M. Benrud-Larson, W. G. Schrage, T. B. Curry, P. Sandroni, P. A. Low, and M. J. Joyner Excessive heart rate response to orthostatic stress in postural tachycardia syndrome is not caused by anxiety J Appl Physiol, March 1, 2007; 102(3): 896 - 903. [Abstract] [Full Text] [PDF] |
||||
![]() |
Y. Cai, S. Holm, M. Jenstrup, M. Stromstad, A. Eigtved, J. Warberg, L. Hojgaard, L. Friberg, and N. H. Secher Electrical admittance for filling of the heart during lower body negative pressure in humans J Appl Physiol, October 1, 2000; 89(4): 1569 - 1576. [Abstract] [Full Text] [PDF] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |