Figure 5. S1P-induced I_NSC in the absence and presence of external Ca²⁺.

A, the same experimental protocol as that in Fig. 2B was applied to a cell that was voltage clamped at -50 mV. The ramp waveform (0.96 V s⁻¹) was applied every 10 s. The scattered noisy spots shown in the original current trace were elicited by these ramp pulses. The original current trace and the change in the current amplitude at -80 and -35 mV, which were close to theoretical reversal potentials of K⁺ and Cl⁻ currents, respectively, are shown. B, the I–V relationship of S1P-induced I_NSC with and without external Ca²⁺. This difference was obtained by subtracting the net membrane current in the absence of Ca²⁺ from that in its presence. Arrows indicate the reversal potential of I_NSC with and without Ca²⁺.