Figure 4.

Tonic block and use-dependent block of I_Ca,L. (a) Original recordings of I_Ca,L obtained under control conditions and in the presence of cinnamophilin (10 μM). I_Ca,L were elicited by 30 consecutive 300 ms depolarizing step pulses to 0 mV (each one preceded by a 150-ms prepulse to −40 mV from a holding potential of −80 mV) at 0.5 Hz (upper) or 2 Hz (lower). The pulse protocol is shown in the inset. For each condition, pulses 1, 2 and 30 are shown. (b) Peak amplitudes of I_Ca,L were normalized to that elicited by the first test pulse before drug application at 0.5 Hz and plotted against the number of pulses applied at different rates in the absence and presence of cinnamophilin (10 μM). Each data point represents means±s.e.mean (n=7). I_Ca,L, L-type Ca²⁺ inward current.