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Fig. 3 | BMC Biology

Fig. 3

From: The retinal pigment epithelium displays electrical excitability and lateral signal spreading

Fig. 3

Fast sodium spikes in current-clamp experiments. A Example of voltage clamp recordings. B Spikes in a current-clamp experiment were evoked by first hyperpolarizing the cell with 100-ms current injections to below −100 mV and then applying depolarizing pulses as indicated. C Separation of a spike (green trace) from the voltage response (black); the region containing a spike was excised and the remaining trace fitted with a first-order exponential rise-to-maximum equation (red); subtracting the traces elicited the spike. Membrane resistance (Rm) was determined from the amplitude of the voltage response (ΔV) to the injected current (Iinj); membrane time constant (τm) obtained by the fitting was used to calculate membrane capacitance (Cm) as indicated. D Examples of spikes; asterisks correspond to the marked traces in B. E Voltage dependencies of membrane resistance, spike amplitude, and spike time to peak in the same experiment; note that the membrane potential refers to the steady-state voltage reached after membrane charging is finished, which is in most cases higher than the potential at which the spike is initiated. F Voltage dependencies of spike parameters: half-widths, 25–75% rise and 75–25% decay times

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