Fig. 8.
Effects of ω-CTx on DPDPE action in ω-Aga and nifedipine-treated cells. The two cells of A andB were preincubated with ω-Aga (250 nm) for 15 min in Tyrode’s solution (2 mm Ca2+) and tested with bath solutions containing 3 μm nifedipine. InA, a short application of 3 μmω-CTx blocked almost all the currents resistant to ω-Aga and DHPs (traces d, e), suggesting that nearly all the inhibitory action of DPDPE (traces a–c) is on N-type channels. In B, ω-CTx blocks only 70% of the ω-Aga- and DHP-resistant currents (traces d,e, h), and DPDPE preserves a strong voltage-dependent action on the residual current that is not N-, L-, or P-type. Test depolarizations to +30 mV fromVh −90 mV. Bars andsymbols are as in Figure 7.