Advances in Physiology Education, Vol 266, Issue 6 10-S15, Copyright © 1994 by American Physiological Society
Demonstration of temperature dependence of Na(+)-K+ pump activity of human blood cells
A. Honig, H. Oppermann, C. Budweg, H. Goldbecher and E. J. Freyse
Institute of Physiology, Ernst-Moritz-Arndt-University of Greifswald, Germany.
In our physiology laboratory course we introduced several simple but
instructive experiments in which medical students make observations on
their own blood cells. In this experiment, students measured and discussed
the effect of different temperatures on Na+ and K+ distribution between
blood cells and plasma. In venous blood of 35 female and 64 male students,
plasma (extracellular) [Na+] and [K+] were measured with ion-selective
electrodes immediately after blood sampling and successively four times in
intervals of 1 h in three samples stored at 1, 20, and 37 degrees C. At 1
degree C, plasma [K+] increased significantly and nearly linearly with
cooling time of the blood, whereas plasma [Na+] decreased. In contrast, at
37 degrees C plasma K+ levels significantly decreased in the first 2 h and
then stabilized at new levels clearly below baselines. At 1 degree C blood
cells had a greater K+ loss in women than in men, whereas at 37 degrees C
the K+ loss was significantly less pronounced in women. Plasma Na+ did not
significantly change at 37 degrees C. This remarkably reproducible
experiment demonstrates the existence of active Na(+)-K+ transport in human
blood cells by showing medical students, with their own blood, that the
basal chemical processes of such pumps are inhibited at a temperature of 1
degree C and stimulated when blood temperature is slightly higher than the
usual body temperature.
