Ryanodine affects the basal rate of exocytotic activity from nerve terminals as measured by amperometry. Amperometric traces provide an example of the effects of ryanodine on spontaneous exocytotic release. Each trace represents sequential 2-min amperometric records from false transmitter–loaded terminals perforated-patched with β-escin, and held at a resting membrane potential of −80 mV in normal Locke’s solution. (Top) The addition of RyR agonist levels of ryanodine (5 µM) results in an increase in the basal release rate. (Bottom) Conversely, the addition of ryanodine at an RyR antagonistic concentration (500 µM) to the bath between the second and third amperometric trace results in a reduction of the basal release rate. (Right) Bar graph summarizing the effects of ryanodine on release across terminals.