Figure 2. The linear effects of temperature on control properties of the GABAAreceptor channel. (A and B) The EC50value for GABA increases, whereas the Hill co-efficient (nH) decreases with increasing temperature. Data are from the least-squares fits in Figure 1. (C) The maximum whole-cell GABA-activated current increases with increasing temperature. Each point gives the maximum response, expressed as a percentage of the response at 20 [degree sign]C. (D) The single-channel conductance increases with temperature. Single-channel currents (see inset for a typical trace at 20 [degree sign]C) from outside-out patches, elicited by 0.1 [micro sign]M GABA at a holding potential of -120 mV, were measured as a function of temperature and converted to single-channel conductances (see Materials and Methods). Each point was obtained using at least five cells. For each plot in A-D, the points give the mean +/− SEM. The continuous straight lines (drawn using the method of weighted least-squares) have no special theoretical or statistical significance but show trends in the data. The dashed lines in C and D are the predicted temperature dependence values (normalized to the values at 20 [degree sign]C) assuming the activation energy of 4,220 cal/mol for diffusion of Cl-ions in water. [26]