Figure 1. Ca²⁺ dependence of exocytosis in somata of MeV neurons.

A, left upper: photomicrograph of MeV neurons in a rat brain slice. Right: C_m jump evoked by a depolarizing pulse (from −60 mV to +10 mV, 100 ms). The Ca²⁺ currents (I_Ca) and {Ca²⁺}_i with Ca²⁺ imaging (F₃₄₀/F₃₈₀) recorded simultaneously. The baseline C_m of the neuron was 53.02 pF (dotted line). The decay of the C_m response was fitted by a single exponential function with τ= 2.1 s (continuous line). B, pre-puffing 0 mm Ca²⁺ attenuated the C_m response (triggered by a depolarizing pulse to +10 mV, 100 ms). Both Ca²⁺ currents and {Ca²⁺}_i decreased. C, statistical bar graph showing pulse stimulation-triggered C_m jumps as in B, that were abolished by 10 mm BAPTA in the pipette. D, C_m jump and Ca²⁺ current as a function of membrane potential. The C_m response was observable at membrane potentials positive to −30 mV, and peaked round 0 mV (n = 8). The Ca²⁺ current was recorded at different depolarizing potentials (100 ms, from −60 mV to 60 mV, +10 mV steps) in different cells (n = 8).