Quiet standing results in hemoconcentration, generally referred to a loss of fluid by transudation to the tissue spaces of the extremities.1 The alterations in the blood are similar to those produced by simple venous stasis.2 Along with a general rise in the concentration of the blood there is a marked increase in the colloid osmotic pressure of the serum under these conditions.3
Man and Peters4 found that the rise in the concentration of plasma protein with standing is paralleled, in general, by rises in the concentrations of cholesterol, fatty acids and lipoid phosphorus in the serum. They concluded that the capillaries are equally impermeable to all these substances. This conclusion is important enough to warrant independent confirmation. In particular it appears that possible osmotic consequences should be studied.
There is still some uncertainty as to whether the capillaries are, under these conditions, completely impermeable to protein.
KEYS A, BUTT HR. FILTRATION PROCESSES IN EXTREMITIES DUE TO STANDING; OSMOTIC ACTIVITY OF PLASMA LIPOIDS. Arch Intern Med (Chic). 1939;63(1):165–172. doi:10.1001/archinte.1939.00180180175012
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