Figure 3. HCN1 deletion results in the loss of the hyperpolarizing effects of GABA_A receptor-mediated inhibition.

(a) Example traces showing voltage responses to current steps injections in wild-type (WT) mice and HCN1 knockout (KO) mice. (b) An example plot showing that, unlike WT mice, HCN1 KO mice lacked a hyperpolarizing GABA_A receptor-mediated driving force. Data points were fitted with a second-order polynomial function. (c) Comparison of V_R in HCN1 KO mice and WT mice (WT: n=5; KO: n=8). (d) Summary plot of E_GABA(A) in both genotypes (WT: n=5; KO: n=4). (e) Sample traces showing that the KO mice displayed no hyperpolarizing phase at V_R, whereas WT animals had a biphasic EPSP–IPSP sequence. The hyperpolarizing IPSPs became apparent in the KO mice when cells were depolarized by DC injection. Conversely, the IPSP was less evident when pyramidal cells from WT mice were hyperpolarized. Error bars represent s.e.m.; **P<0.01.