Disappearance of the difference between adrenal A and NA cells in the level of radioactivity after 3H-dopa injection in the hypophysectomized mouse.

Radioactivity in adrenal medullary chromaffin cells of the mouse was examined by autoradiographic methods 15 min to 1 hr after an intraperitoneal injection of 3H-dopa. In the normal control mice, the concentration of radioactivity was significantly higher in the A cells than in the NA cells, whereas in the hypophysectomized mice (9 days after operation by the transauricular method) the radioactivity was evenly distributed in the two cell types. It was suggested that both A and NA cells possessed a special trapping and concentrating mechanism for extracellular dopa and/or its metabolites and that the activity of this mechanism was made greater in the A cells than in the NA cells by the pituitary gland.