Effect of 20 days bed rest upon peripheral capillary filtration rate, venous compliance and blood flow in arms and legs.

Capillary filtration rate, venous compliance and blood flow in arms and legs were measured during bed rest by strain gauge plethysmography using a liquid metal alloy in silastic tubes. Furthermore orthostatic tolerance to lower body suction was recorded. Six young healthy males and three young healthy females participated in the 20 days bed rest study. Neither arm nor leg blood flow was changed by bed rest. Arm blood flow varied between 2.18 +/- 0.30 and 3.03 +/- 0.35 vol%.min-1 and leg blood flow between 1.42 +/- 0.12 and 1.76 +/- 0.40 vol%.min-1. The capillary filtration rate tended to decrease in the arms from 0.27 +/- 0.07 vol%.min-1 at day 0 to 0.17 +/- 0.03 vol%.min-1 at day 3 and a tendency to an increase in filtration rate in the legs from 0.16 +/- 0.06 at day 0 to 0.56 +/- 0.21 vol%.min-1 at day 3 but both of these changes had recovered from day 10 on. There was a steady state in venous compliance of the forearm between 1.31 +/- 0.20 and 1.50 +/- 1.13 vol% during the first two weeks of the bed rest period but the values tended to increase to 1.75 +/- 0.16 and 1.89 +/- 0.22 vol% at days 16 and 19, respectively, while leg venous compliance showed a transient tendency to increase at day 3 (from 0.83 +/- 0.08 at day 0 to 1.30 +/- 0.32 vol% at day 3) to attain control values from day 5. Orthostatic intolerance measured during lower body suction decreased in the present subjects.(ABSTRACT TRUNCATED AT 250 WORDS)