Figure 3: The surface density of voltage-activated potassium channels is under-estimated in cell-attached recordings.
From: Errors in the measurement of voltage-activated ion channels in cell-attached patch-clamp recordings
(a) Leak-subtracted ensemble potassium channel activity (IC-A) generated in response to a voltage step protocol (Vp) during simultaneous whole-cell voltage- (left) and current-clamp recording from the soma of a thalamocortical neuron. Cell-attached currents were accompanied by the generation of a whole-cell recorded outward current (IW-C) or a hyperpolarizing voltage response (Vm) under voltage- or current-clamp conditions, respectively. (b, c) Linear relationship between the amplitude of ensemble potassium channel activity recorded in cell-attached patches and as whole-cell current (open symbols) when measured at peak (b) and steady state (c). Filled symbols illustrate the magnitude of ensemble potassium channel activity recorded from the same patches under whole-cell current-clamp conditions, and are plotted with reference to the value of whole-cell current recorded under voltage-clamp mode for each patch. Data have been fit by linear regression or with an exponential function (lines). (d) The amplitude of intracellular voltage responses recorded under whole-cell current-clamp generated by ensemble potassium channel activity in cell-attached patches. Voltage responses were measured at time points corresponding to the peak amplitude (peak) of the cell-attached current or at steady state. Pooled data (n=32) are represented as mean±s.e.m.
