Figure 3.

Gal inhibited the GCs and reduced ACh release. (A) Samples of GCs induced by depolarizing the oocyte from −120 mV to −40 mV at different concentrations of Gal. Inset shows the pulse protocol. (B) Normalized DI_GCs curves for Gal. In each oocyte, GCs were measured in control and with one concentration of Gal (n = 4–10 for each point taken from 6 donors). IC_50-GCs = 0.89 ± 0.05 µM. (C) A representative experiment depicting the dose-dependent effect of Gal on the EPSC size. Washing Gal restored the control values of the EPSC. The quantum size (×), monitored throughout the experiment by measuring the size of asynchronous single quanta released more than 50 ms after depolarization, remained constant. (D) Evaluation of the quantal content (m) from $m=\frac{\stackrel{-}{\mathit{EPSC}}}{\stackrel{-}{\mathit{mEPSC}}}$ (empty bars), where $\stackrel{-}{\mathit{EPSC}}$ is the average EPSC and $\stackrel{-}{\mathit{mEPSC}}$ is the average size of a single quantum, and from $m=\mathrm{In}\frac{N}{N_0}$ (full bars), where N is the number of pulses applied and N₀ is the number of failures. As seen, the two methods produced similar values of m (n = 6). (E) Ca²⁺ currents without (solid line) and with (dashed line) 10 µM Gal (representative experiment, n = 3). (F) Superimposed average EPSCs (n = 5) recorded in M₂KO mice in control (solid line) and with 5 µM Gal (dashed line). (G) DI_release curve (■, n = 8) for Gal constructed from experiments such as those in C (IC_50-release = 0.85 ± 0.07 µM) compared with the DI_GCs curve of Gal (taken from B). (H) Rate of spontaneous release (in WT mice) in control (white), and with 5 µM Gal (gray; n = 5).