Figure 3.
Modulation of ICa at the Mb terminal is Ca2+-dependent and required synaptic signaling. A, Average (leak-subtracted and normalized) stepwise I-V curve from axotomized terminals in slice preparation (n = 13 for steps to ≤−10 mV, n = 9 for steps to 0 mV and 20 mV). Consecutive I-V curves were generated 3 min apart by using 3 ms voltage steps. Data were fitted with a modified Boltzmann equation, smooth line (black represents first, control I-V; red represents second I-V). Data are mean ± SEM. B, Chelation of ramp-evoked Ca2+ influx using BAPTA (10 mm) inhibited strong depolarization-induced modulation of ICa kinetics of axotomized terminals in retinal slice preparation. C, Consecutive ICa I-Vs recorded from the axon terminal of an enzymatically dissociated, solitary Mb. The voltage ramp protocol was the same used in slice preparation. No shift was observed between the control (black) and the second (red) ICa I-Vs.