Figure 7: Measurement errors of dendritic HCN channels in cell-attached patches.
From: Errors in the measurement of voltage-activated ion channels in cell-attached patch-clamp recordings
(a) Intracellular voltage change (Vm) evoked by ensemble HCN channel activity (IC-A) simultaneously recorded from the apical dendrite of a layer 5 pyramidal neuron (840 μm from the soma, separation between cell-attached and whole-cell pipette=10 μm). (b) Linear relationship between the amplitude of ensemble HCN channel activity in cell-attached patches and intracellular depolarization at apical dendritic sites of layer 5 pyramidal neurons. Data were gathered at room (23–24 °C, filled symbols) or near physiological (35–37 °C, open symbols) temperatures, and were fit by linear regression (lines). (c) Voltage-dependent activation of ensemble HCN channel activity (IC-A) in a cell-attached patch recorded from the apical dendrite of a layer 5 pyramidal neuron (850 μm from the soma). The lower traces show the intracellular voltage responses simultaneously recorded under whole-cell current-clamp (Vm; 9 μm separation between pipettes). Note the generation of AP firing. (d) Pooled data demonstrating the linear relationship between HCN channel activity in cell-attached patches and intracellular depolarization, when measured at steady-state (filled symbols, fit by linear regression, line), but the minimal voltage deviation apparent at the peak of HCN tail currents (open symbols). Pooled data (n=7) represent mean±s.e.m. (e) Transmembrane voltage corrected activation curve of apical dendritic HCN channels. Pooled data (n=7, mean±s.e.m.) have been fit with a single Boltzmann function.
