EXOCYTOTIC RELEASE FROM INDIVIDUAL GRANULES EXHIBITS SIMILAR PROPERTIES AT MAST AND CHROMAFFIN CELLS

The effects of temperature on granular secretion were studied in indiv idual bovine adrenal chromaffin and rat peritoneal mast cells. It was found that more molecules are released from individual granules at phy siological temperature than at room temperature, where such experiment s are normally performed. In mast cells, there is also a dramatic decr ease in the time required for exocytosis to be complete at 37 degrees C compared to room temperature, In the presence of some cations, the a mount released from individual granules at room temperature from both types of cells could be altered. The amount of secretion decreased wit h the divalent cation zinc but increased with the monovalent cation ce sium. These experiments used two electrochemical techniques: cyclic vo ltammetry and amperometry. With amperometry, the concentration gradien t created by the electrode near the cell further increased the amount of release. Similar responses to changes in the extracellular environm ent in chromaffin and mast cells suggest that the mechanism of extrusi on of the granule contents is similar in both cell types.