Neher and Sakmann also used the electrode pipette to inject different agents into the cell, and they could thereby investigate the different steps in the secretory process within the cell itself (see above). In this way a number of cellular secretory mechanisms have been clarified such as the role of cyclic AMP (see Nobel Prize to Sutherland 1971) or calcium ions. For instance, we now have a better understanding of how the hormone levels in the blood are maintained at a certain level.