Journal of Applied Physiology, Vol 59, Issue 6 1686-1689, Copyright © 1985 by American Physiological Society
Volume and density changes of biological fluids with temperature
H. Hinghofer-Szalkay
High-precision (10(-5) g/ml) mass density measurements on human blood,
plasma, plasma ultrafiltrate (using PM-10 membranes), and erythrocyte
concentrate samples were performed with the mechanical oscillator
technique. Measurement temperatures varied between 4 and 48 degrees C and
were accurate to +/- 1 X 10(-2) K. The coefficient of thermal expansion
(beta), defined as relative volume change with temperature, was calculated.
It was shown that beta increases with temperature in these fluid samples
over the entire temperature range investigated; the magnitude of this
increase declines with increasing temperature; beta increases with density
at temperatures below 40 degrees C but is independent of density above 40
degrees C; and the beta of the intracellular fluid has about twice the
value of the beta for extracellular fluid at low (4-10 degrees C)
temperatures but is equal for both fluids at greater than or equal to 40
degrees C. The mechanical oscillator technique provides data with an
accuracy sufficient to perform precise (10(-5) K) calculations of beta of
small volumes of biological fluids.
