Figure 3.

Inhibition of Ca²⁺ currents in acutely dissociated-sympathetic neurons by the N-type Ca²⁺ channel blockers ω-CTX (a) and Cd²⁺ (b). Cells were held at −80 mV. Voltage-activated Ca²⁺ currents were triggered by voltage steps of 120 ms duration from the holding potential (−80 mV) to 0 mV. This depolarizing step was applied once every 20 s. In (a), the individual records that comprise the averaged peak current amplitudes (−1.16±0.05 nA, n=6 stimuli) ranged from −1.27 to −0.95 nA in control conditions, whilst the individual records comprising the averaged peak response made after treatment with ω-CTX ranged from −0.18 to −0.15 nA. In the Cd²⁺ experiments (b), an analysis of variance followed by multiple comparisons using Bonferroni's method revealed highly statistically-significant differences between control (−1.16±0.03 nA, n=6) and Cd²⁺ treatment (−0.18±0.02 nA, n=6) and between Cd²⁺ exposure and the wash period (−1.14±0.03 nA, n=3; P<0.05) but not between the control and wash periods. For further details of the N-type Ca²⁺ currents in acutely-dissociated autonomic neurons in guinea-pig (see Barajas-Lopez et al., 1996).