The dynamics of Gm in AP-firing fibers were more closely related to the number of APs fired than to the experimental duration. Experiments were conducted similar to that presented in Fig. 2 except that the frequency of the AP trains was varied. (A–C) Recordings from representative fibers in which the APs were triggered using trains of 6 Hz (A), the usual 15 Hz (B), or 30 Hz (C). Enlargements of the underlined parts in the recordings of the membrane potential have been included below. (D) Gm at the three frequencies have been plotted against the experimental time. At all frequencies, ∼5,000 APs were fired, and the fibers were allowed to rest for 1 min before recovery of Gm was assessed. Arrows indicate Gm 1 min after cessation of AP firing. (E) Gm at the three frequencies have been plotted against the number of APs fired. (D and E) Mean data from eight fibers at 6 Hz, 18 fibers at 15 Hz, and 13 fibers at 30 Hz. For clarity of mean data, only every fifth error bar (SEM) has been included.
