MICROFILAMENTS REGULATE THE RATE OF EXOCYTOSIS IN RAT BASOPHILIC LEUKEMIA-CELLS

Disruption of microfilaments in rat basophilic leukemia (RBL) cells by exposure to cytochalasin B is observed to potentiate the rate of antigenstimulated secretion from these cells. Under these conditions, cytochalasin B is without effect on the antigen-stimulated production of inositol phosphates or 45Ca2+-influx. In streptolysin-O-permeabilized RBL cells, cytochalasin B is observed to potentiate the rate of secretion in response both to guanosine 5′-(2-thio)-O-triphosphate (GTPγS) and to Ca2+ (buffered between 0.1 and 10 μM). However, under these conditions, cytochalasin B does not affect to antigen-stimulated production of inositol phosphates. Consistent with these data, microfilaments are proposed to regulate a terminal step in exocytosis, in a physiologically relevant manner. © 1990.