TY - JOUR
T1 - Leg venous compliance in orthostatic intolerance before and after 14-day head-down bed rest.
AU - Fu, Qi
AU - Iwase, S.
AU - Kamiya, A.
AU - Michikami, D.
AU - Niimi, Y.
AU - Mano, T.
PY - 2000/12
Y1 - 2000/12
N2 - To test the hypothesis that increased leg venous compliance (LVC) is one of the contributory factors to orthostatic intolerance (OI) after simulated microgravity, 28 healthy young males were exposed to a 14-day head-down bed rest, and LVC was measured by venous occlusion plethysmography. Orthostatic tolerance was evaluated by a 60 degree head-up tilt (HUT) for 15 min. Sixteen subjects suffered from OI after the bed rest. They were then divided into orthostatic tolerance (non-fainters, n=12) and intolerance (fainters, n=16) groups. We found that fainters had significantly larger LVC before bed rest (0.055 +/- 0.003 vs. 0.065 +/- 0.002 ml 100 ml-1 mm Hg-1, non-fainter vs. fainter; P < 0.05). After bed rest, LVC markedly increased in both groups. In all the subjects calf circumference was reduced on average by 4.7% and the percent change in LVC was negatively correlated with the percent change in calf circumference when all subjects' data were combined after bed rest (r = -0.42, P < 0.05). Our results did not support the hypothesis that increased LVC is the contributory factor to OI after a 14-day bed rest; however, the mechanisms behind the large LVC in the fainters before bed rest are unclear, and the initial LVC might be a predictive indicator for OI after microgravity exposure.
AB - To test the hypothesis that increased leg venous compliance (LVC) is one of the contributory factors to orthostatic intolerance (OI) after simulated microgravity, 28 healthy young males were exposed to a 14-day head-down bed rest, and LVC was measured by venous occlusion plethysmography. Orthostatic tolerance was evaluated by a 60 degree head-up tilt (HUT) for 15 min. Sixteen subjects suffered from OI after the bed rest. They were then divided into orthostatic tolerance (non-fainters, n=12) and intolerance (fainters, n=16) groups. We found that fainters had significantly larger LVC before bed rest (0.055 +/- 0.003 vs. 0.065 +/- 0.002 ml 100 ml-1 mm Hg-1, non-fainter vs. fainter; P < 0.05). After bed rest, LVC markedly increased in both groups. In all the subjects calf circumference was reduced on average by 4.7% and the percent change in LVC was negatively correlated with the percent change in calf circumference when all subjects' data were combined after bed rest (r = -0.42, P < 0.05). Our results did not support the hypothesis that increased LVC is the contributory factor to OI after a 14-day bed rest; however, the mechanisms behind the large LVC in the fainters before bed rest are unclear, and the initial LVC might be a predictive indicator for OI after microgravity exposure.
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M3 - Article
C2 - 11758569
AN - SCOPUS:0034571189
SN - 0287-0547
VL - 44
SP - 53
EP - 55
JO - Environmental medicine : annual report of the Research Institute of Environmental Medicine, Nagoya University
JF - Environmental medicine : annual report of the Research Institute of Environmental Medicine, Nagoya University
IS - 1
ER -