Monensin depletes PC12 pheochromocytoma cells of catecholamines and of chromaffin-type granules

Abstract

PC12 pheochromocytoma cell store dopamine in chromaffin-type granules. The carboxylic ionophore momensin depletes the cells of dopamine and of granules PC12 cultures incubated for 30 min with 100 nM monensin lose more than 90% of their dopamine. A small fraction of the dopamine that disappears from the cells is converted to dihydroxyphenylacetic acid. The remainder is presumably converted to other, unidentified metabolites. Monensin-treated cells contain many cytoplasmic vesicles. Some of these vesicles contain amorphous, electron-dense material, which may represent the matrix of disrupted granules. There is no morphological evidence of exocytosis. Thus, monensin appears to promote the intracellular lysis of chromaffin-type granules in PC12 cells.