Influence of reduction of cytoplasmic ATP on catecholamine secretion from intact and digitonin-permeabilized adrenal chromaffin cells.

The effect of the metabolic inhibitor 2,4-dinitrophenol (DNP) on the concentration of cytoplasmic ATP and the activity of catecholamine secretion was studied using cultured bovine adrenal chromaffin cells. The pretreatment of the cells with DNP resulted in a decrease in the concentration of cytoplasmic ATP. Catecholamine secretion evoked by either carbamylcholine or high K+ was also reduced by DNP pretreatment. Oligomycin caused a significant decrease in both cytoplasmic ATP concentration and catecholamine secretion. In contrast, neither the ATP level nor the secretory response was affected by 2-deoxyglucose. Similarly, catecholamine release from digitonin-permeabilized chromaffin cells in response to a direct calcium challenge was reduced by pretreatment of the cells with DNP, and this reduction was partially prevented by the presence of ATP in the permeabilizing medium. These results suggest that ATP in the cell cytoplasm may play an important role in the regulation of catecholamine secretion as a factor modulating the activity of the exocytotic process in the adrenal chromaffin cell.