Effect of Epinephrine in Decreasing Number of Circulating Mononuclear Leucocytes in the Rat.

Conclusions The administration of epinephrine to normal or adreno-demedullated rats produced within 2 hours a definite fall in the number of circulating mononuclear leucocytes. The number of mononuclears did not decrease after administering epinephrine to adrenalectomized rats. This indicates that the presence of the adrenal cortex is necessary for epinephrine to cause these effects. After administering epinephrine to hypophysectomized rats, the number of mononuclears decreased as in the epinephrine treated normal rats although the percentage decrease was less. This would seem to indicate that at least one effect of epinephrine is to act directly on the adrenal cortex, releasing substances which lower the level of circulating mononuclear leucocytes. Since this paper was submitted for publication, Gellhorn and Frank15 have reported that epinephrine causes a reduction in the number of circulating lymphocytes in normal but not in adrenalectomized rats.