Figure 7. GABA-activated responses at pH 6.4 on cerebellar granule neurones: inhibition by Zn²⁺.

A, whole-cell currents recorded for 1 μm to 2.5 mm GABA in the absence (upper panel) and presence of 300 μm Zn²⁺ (lower panel). Holding potential, −40 mV. B, GABA concentration-response curves are plotted at pH 6.4 in the absence (^) and presence (•) of 300 μm Zn²⁺. The continuous line curve fit was provided by the logistic model (see Methods). For comparison, the dotted lines plot the corresponding curves for data obtained at pH 7.4 (see Fig. 6).