Temperature dependence of the K+ fluxes between cells and plasma in the whole blood of normotensive and primary hypertensive young men

Samples of venous blood were taken from 24 sons of normotensive parents (SO NT) and 24 sons of primary hypertensive parents (SOHT) aging 21 - 27 years. The heparinized but otherwise untreated blood samples were stored for 3 ho urs at 15 different temperatures between 1 degrees C and 37 degrees C. Ln t he range 20 degrees C to 25 degrees C only negligible changes of plasma Koccurred. Below 20 degrees C plasma K+ increased without a plateau reaching a maximum at 1 degrees C. Between 29 degrees C and 37 degrees C plasma Kdecreased. Only in the SOHT and only at 33 degrees C the K(+)fall in the pl asma correlated significantly and negatively (r = -0.66, p < 0.001) with th e renin content of the fresh blood. No significant differences could be obt ained between the Ki-fluxes in the blood of SONT and in that of SOHT. The d ata suggest that below 20 degrees C with falling temperature not only an in creasingly effective cold-blockade of the Na+/K+-ATPase but also changes of blood cell membrane fluidity and/or structure occcur. The fall of plasma p otassium at temperatures between 29 degrees C and 37 degrees C could specul atively be explained by the assumption that physiologically existing inhibi tors of the Na+/K+-pump in the blood in vivo disappear in vitro which would result in a transiently elevated activity of this ion transporter. The det ermination of the temperature dependence of the K+-fluxes in the whole bloo d does not support the diagnosis of primary hypertension in humans.