Fig. 4: K⁺ currents are similar in WT and Kcnb1^R312H(+/+) primary neurons.

A, B Representative image of a typical cortical pyramidal neuron patched to a glass pipette and RT-PCR amplification of Kcnb1, VGluT1, and for control, Glyceraldehyde 3-phosphate dehydrogenase (GAPDH), mRNA transcripts. RT-PCR was carried out using the cell’s cytoplasm collected at the end of the electrophysiological recording as described. Scale bar 20 μm. C Representative whole-cell currents elicited in a WT or Kcnb1^R312H(+/+) pyramidal neuron. Cells were clamped at −80 mV and currents were evoked by 0.5 s voltage steps from −80 mV to +80 mV in 20 mV increments (inset). D Mean macroscopic current-voltage relationships for WT and Kcnb1^R312H(+/+). N = 40 cells/genotype. E Macroscopic normalized conductances (G/G_Max) for WT and Kcnb1^R312H(+/+). G/G_Max were calculated according to Eq. 1, averaged, and fitted to the Boltzmann function (Eq. 2) with V_1/2 = −1.18 mV and V_s = 14.9 mV for WT and V_1/2 = 2.09 mV and V_s = 15.2 mV for Kcnb1^R312H(+/+). N = 40 cells/genotype. F Representative variance-mean current plots for WT and Kcnb1^R312H(+/+). Currents were evoked by 10–20, repetitive voltage jumps from −80 mV to +40 mV. Data were fitted to Eq. 5 with i = 6.3 pA, N_c = 558 channels for WT and i = 5.1 pA, and N_c = 543 channels for Kcnb1^R312H(+/+). The estimated p₀ at +40 mV (Eq. 6), is ∼0.5 for both genotypes. G Representative WT and Kcnb1^R312H(+/+) currents at +80 mV in the absence/presence of 100 nM Guangxitoxin (GxTx) in the bath. H Quantifications of WT, Kcnb1^R312H(+/+), and Kcnb1^NULL(+/+) current amplitudes at +80 mV in the absence/presence of 100 nM GxTx in the bath. All recordings were performed using DIV14 neurons, obtained from N = 7 WT brains, N = 7 Kcnb1^R312H(+/+) brains, and N = 5 Kcnb1^NULL(+/+) brains with three dishes/brain. ^*P < 0.05, ^***P < 0.001, and ^****P < 0.0001, one-way ANOVA with Tukey’s post hoc test.