Figure 3

Hyperforin induces a proton-dependent current in microglial cells.

Inward and outward currents at −80 and +80 mV, respectively, from primary mouse microglial cells (a, d, h, j). As indicated by the bars either 10 μM hyperforin was applied at different external pH (pHx; a) or external pH was changed in the absence (h) or during 10 μM hyperforin (d) or 10 μM CCCP (j) application. Currents were normalized to the cell size and basic currents before compound application were subtracted. The corresponding IVs are displayed in (b, e, i) and (k). (c, f) and (l) show the change of the reversal potentials, during the experiments in (a, d) and (j), respectively. Note that the reversal potentials of the hyperforin- and CCCP-induced currents change with different external pH (see c, f and l) and that the IVs and the pH 5.4-dependent changes of the reversal potential are similar for hyperforin- and CCCP-induced currents (see e and k as well as f and l, respectively). In (g) all experimentally obtained values of reversal potentials of the hyperforin-induced currents (black dotes) are plotted versus the external pH (intracellular pH 7.2). The dotted red line in (g) depicts the H⁺ reversal potentials calculated via the Nernst equation for a proton current at intracellular pH 7.2 and external pH as indicated (see experimental procedures). Data represent means ± S.E.M. of the indicated number of experiments (cells).