Figure 9.

Sodium current contributes to the temperature-sensitive background conductance. A, Comparison of conductance at −65 mV in control ACSF and after substitution of 100 mm external Na⁺ with choline. In choline–ACSF, the background conductance was reduced by 13% (from 0.67 ± 0.26 to 0.59 ± 0.28 nS) at 30 ± 0.3°C and by 49% (from 0.81 ± 0.38 to 0.41 ± 0.29 nS) at 38.8 ± 0.5°C. B, Average conductance recorded in control ACSF + 100 μm CdCl₂ and in choline–ACSF + 100 μm CdCl₂. Conductance was reduced by 21% (from 0.41 ± 0.13 to 0.33 ± 0.12 nS) at 30.3 ± 0.2°C and by 41% (from 0.65 ± 0.24 to 0.38 ± 0.16 nS in choline) at 39.4 ± 0.3°C. C, Gadolinium-sensitive current (obtained by offline digital subtraction) recorded at 28.9°C (black trace) and 38.7°C (gray trace). D, Average gadolinium-sensitive current measured in CA1 pyramidal cells at −65 mV. No significant current (0.51 ± 0.3 pA, n = 3) was observed at 29.9 ± 0.5°C, whereas at 38.7 ± 0.2°C (n = 4), the current had a mean amplitude of −32.3 ± 5.3 pA.