Enhancement by F-actin of MgATP-dependent dopamine uptake into isolated chromaffin granules

Interaction of chromaffin granules with the microfilament network in the cytoplasmic space of adrenal medullary cells has been proposed, but the influence of chromaffin granule-microfilament interaction on granule function has not yet been studied. In the present study, the effect of F-actin on dopamine uptake into isolated chromaffin granules was examined. The MgATP-dependent component of dopamine uptake was significantly enhanced by F-actin. In contrast, catecholamine efflux from the granules was not significantly altered by F-actin under the conditions in which the enhancement of MgATP-dependent dopamine uptake was observed. These findings suggest that the interaction of chromaffin granules with the microfilament network results in the enhancement of MgATP-dependent dopamine uptake into the granules, thus modulating the accumulation and storage of catecholamines in the adrenal medullary cell.