Uptake of [3H]dopamine in the mouse adrenal medulla during dark and light period

Uptake of exogenous [3H]dopamine in adrenal chromaffin cells of the mouse was studied by autoradiography under a 12-h light, 12-h dark cycle. The uptake of [3H]dopamine in adrenal chromaffin cells was markedly decreased in the dark period. The decrease was prevented by adrenal denervation. It is postulated that there is a neurally mediated suppression of [3H]dopamine uptake by adrenal chromaffin cells in the dark period. Adrenaline-storing (A) cells are more sensitive to the decreased sympathetic activity than noradrenaline-storing (NA) cells while increased sympathetic activity non-selectively affects both types of adrenal chromaffin cells.