Fig. 3.

A PKC antagonist BIS blocks in large part the effect of PMA on the capacitance jump. A, Sample recordings of presynaptic Ca²⁺ currents (ICa, top) and capacitance changes (Cm, bottom) evoked by a 2 msec presynaptic step from −80 to +10 mV in the control (left), in the presence of BIS (1 μm) for 10 min (middle left), and in the presence of BIS (1 μm) plus PMA (100 nm) for 10 min (middle right). These traces are superimposed on theright for comparison. B, Percentage of increase in the capacitance jump (ΔCm) evoked by a 2 msec step depolarization to +10 mV during the application of 1 μm BIS (n = 6), 1 μmBIS plus 100 nm PMA (n = 6), and 100 nm PMA (n = 6). The percentages refer to the changes in capacitance jumps during the application of the drug or drugs normalized to the value obtained before any drug application at the same synapse. Data are expressed as means ± SE.