ADRENAL-MEDULLARY SECRETORY RESPONSE TO STIMULATION OF THE MEDULLA-OBLONGATA IN THE RAT

In rats anesthetized with sodium pentobarbital, adrenal venous blood samples were collected and analyzed for epinephrine and norepinephrine by the fluorometric method. Stimulation of the inferior fovea or adjacent areas resulted in a significant increase in epinephrine secretion. Stimulation of some other areas of the floor of the fourth ventricle was associated with a significant decrease in norepinephrine secretion with or without significant decrease in epinephrine secretion. In no instance was observed a significant increase in norepinephrine secretion in response to the medulla oblongata stimulation.