Fig. 1

Measurements of EC₅₀ of Li⁺ inhibition of NMDA-elicited currents before and after the cholesterol extraction. a Currents activated by 100 μM NMDA + 10 μM Gly recorded in the bathing solutions containing different Li⁺ concentrations ([Li⁺], % is indicated on the right of each trace) at − 55 mV before and after 5 min treatment with 1.5 mM MβCD. The insert in the box represents an example of I/V measurements before (black curve) and after (green curve) the MβCD treatment. The protocol of “ramp” is indicated by the red line above the records. b Concentration-inhibition curves for Li⁺ of currents activated by 100 μM NMDA + 10 μM Gly. The mean values ± S.E.M. from 10 experiments for each of the conditions are plotted. Solid lines indicate fits of the data with the Hill equation with the parameters: IC₅₀ = 46 ± 21 mM and h = 2.3 ± 0.8 (n = 10) in control conditions and 42 ± 20 mM and h = 3.3 ± 1.0 (n = 10) after the MβCD treatment. Abscissa is the Li⁺ concentration in the external solution presented as the absolute value ([Li⁺], mM) and the ratio of [Li⁺] to the sum of Na⁺ and Li⁺ concentrations of 140 mM ([Li⁺], %). c The same curves as on (b) normalized to I_max to illustrate the difference in the extent of the Li⁺ inhibition of currents, activated by NMDA before and after the MβCD treatment. d Histogram of fractions of residual currents (I_min) obtained at 140 mM Li⁺ ([Li⁺], 100%) in the external solution before (control) and after the MβCD treatment (MβCD) to the value of I_max, drown from the fits (mean values ± S.E.M. for each of the conditions, n = 10). ** the value is significantly different from the corresponding value obtained under control conditions (p < 0.01, Student’s two-tailed t-test)