Fig. 4. K+ current block by tetraethylammonium (TEA+) is dissimilar between male and female vomeronasal (VN) neurons. Dose/response curves for TEA+ block of K+ currents in female (A,B) and male (C,D) VN neurons. Whole-cell currents were elicited using the voltage stimulation protocol described in Fig. 3, and neurons were pretreated with 20 nmol l–1 tetrodotoxin (TTX) to isolate predominantly outward currents. The initial current at +40 mV depolarization was normalized to that after a 5 min incubation with bath-applied TEA+ at various concentrations. Peak transient current was measured 50 ms after the beginning of the voltage stimulation, and peak sustained current was measured at the end of the 400 ms duration of the voltage stimulation. The smooth curves are fits to a single-exponential decay, where y=yo+Ae–(x–x0)t, with a half-maximal inhibition concentration (Ki) for the transient K+ current of 2.4 µmol l–1 and 2.0 µmol l–1 for male and female neurons, respectively. The sustained K+ current had a Ki of 4.8 µmol l–1 and 1.7 µmol l–1 for male and female neurons, respectively. Values are means ± S.E.M. (sample sizes are given on the figure).
