Figure 7
Ionic basis and pharmacology of inward currents generated by AE in neural cells. (a) Traces illustrate typical current response elicited by AE (1 mg ml−1) at different potentials either in neurons or in oligodendrocytes; in both cases extract generated inward currents that presented an Erev close to 0 mV. (b) Current–voltage relationship for the response to AE were monitored in neurons in two conditions, first in control external solution containing 146 mM Cl− (dark orange circles) and then the same cell in external solution containing 36.5 mM Cl− (light orange circles). In low Cl− external solution the Erev shifted to more positive potentials. (c) Bicuculline (30 μM) was tested for its effect on the inward current response elicited by AE (0.5 mg ml−1). Neurons were tested for their response either to 5 μM GABA (black traces) or to AE (orange traces) and then the inhibitory effect of bicuculline (blue traces) was tested in each case. For GABA response bicuculline showed a strong inhibitory effect in all cases, while the effect on AE-elicited response was less potent and more variable between different neurons (two different neurons are illustrated). (d) In similar experiments, picrotoxin (30 μM, blue traces), inhibited in comparable manner to both the GABA- and the AE-response. (e) Normalized responses (mean ± S.D.) obtained in 8 neurons for each condition are shown in the bar graph. Current response in the presence of each drug was normalized against the corresponding amplitude reached by either GABA or AE applied alone (*p < 0.05 for comparisons between the GABA vs. AE amplitude values in the presence of bicuculline).
