Figure 2.

Capacitance measurements of exocytosis induced by photolysis of the caged compound DM-nitrophen in TeTx-treated wild-type PC12 (A and B) and defective PC12-27 (C and D) cells. A–D match the corresponding panels of Fig. 1. From the comparison of the figures emerges a marked decrease of both the fast and slow components and the slowing of the fast component in the wild-type cells (compare Fig. 2A to Fig. 1A). In contrast, no change of the capacitance responses was detected in PC12-27 cells (compare Fig. 2C to Fig. 1C). From the initial capacitance increases recorded with high time resolution (B and D; cells shown are different from those in A and B), the time constant in the wild-type PC12 was approximated to 410 msec. In the PC12-27 cell, the increase could be fitted by using the sum of two exponential functions with time constants of 68 msec and 1.1 sec, comprising ≈20 and 80% of the response, respectively.