Figure 3. Rabbit chemoreceptor cells express L-, N-, P/Q- and R-type calcium channels.

A shows the time course of I_Ca recorded in perforated-patch configuration of the voltage-clamp technique in a representative cell. Currents evoked by voltage pulses to +10 mV from a holding potential of –80 mV were recorded during superfusion of the cells in control conditions and during the cumulative addition of nisoldipine (Nis; 2 μm), ω-conotoxin GVIA (GVIA; 1 μm), ω-conotoxin MVIIC (MVIIC; 3 μm) and CdCl₂ (Cd²⁺; 200 μm) to the bath solution. Current traces obtained at the times indicated by numbers are shown in the inset. B shows fractional composition of the total calcium currents recorded at +10 mV in chemoreceptor cells (see text). Filled bars correspond to data obtained in perforated-patch recordings following the protocol shown in A. Open bars correspond to data obtained in whole-cell recordings showed in Fig. 2; the percentage of I_Ca carried through P/Q channels in the whole-cell recordings is not shown since it was not directly explored (see Fig. 2). n = 5–7 cells in every case.