The effect of single cerebroside compounds on activation of BK_Ca channels

Figures & data

Figure 1. Effect of intracellular Ter A and Ter B on the BK_Ca channels. (A) Chemical structures of Ter A and Ter B. (B) Representative single channel recordings in the absence and presence of Ter A or Ter B at +20 mV. Arrows indicate the closed state of the channel. The Po values for each trace are indicated at the right. (C) Statistical data for mean Po of the BK_Ca channels in the presence of Ter A (10 μM) or Ter B (10 μM). **p < 0.005 compared to the control.

Figure 2. Time course of the BK_Ca channel activation by intracellular Ter A. Time course of single channel recordings in control condition (A) or upon intracellularly application of Ter A (B). 0 min denotes the time point of intracellularly application of DMSO or Ter A. (C) Current-voltage relationship for single-channel activities before and after application of Ter A. Each point represents mean ± SEM for at least 4 patches.

Figure 3. Dose-dependent effects of intracellular Ter A on the BK_Ca channels. (A) Representative single BK_Ca channel traces at +20 mV in the control and during successive exposure to different concentration of Ter A (1.25–10 μM) in the same patch. (B) Ter A increase the Po of BK_Ca channels in a dose-dependent manner. The curve is the best fit to Po against the [Ter A] according to the Hill equation. (C) Current traces before, during application and washout of 10 μM Ter A. (D) Statistical summary for the washout experiment. **p < 0.005 compared to the control and washout condition.

Figure 4. Effect of extracellularly applied Ter A on the BK_Ca channels. (A) Effect of 150 μM extracellular Ter A on Po over time at +20 mV. The recordings start (0 min) at the time when the inside-out patch was formed. Arrows indicate the closed state of the channels. (B) Statistical results of extracellular Ter A (10–150 μM) on Po of the channel at 10 min after formation of a giga-ohm seal at +20 mV. Values are mean ± SEM. **p < 0.005 compared to the control.

Figure 5. Effect of Ter A on the Ca²⁺-dependence of BK_Ca channel activation. Representative single channel current traces of the BK_Ca channels at [Ca²⁺]_i ranging from 1 nM–50 μM before (A) and after (B) intracellular application of 10 μM Ter A at +20 mV. (C) The relationship between Po and [Ca²⁺]_i in the absence and presence of 10 μM Ter A are fitted to a modified Hill equation (see text for detail). Each point is the mean ± SEM from at least five experiments.

Figure 6. Effect of Ter A on the voltage-dependence of the BK_Ca channel activation. Representative single channel current traces of the BK_Ca channels at membrane potentials ranging from −50 to +60 mV in the absence (A) and presence (B) of 10 μM Ter A. (C) The relationships between the mean Po of the BK_Ca channels and the membrane potentials in the absence and presence of Ter A (1.25–10 μM) are fitted with the Boltzmann equation (see text for detail). Only the error bars for the control and 10 μM Ter A are shown for clarity.

Figure 7. Comparison of the effect of Ter A on the activation of wild-type and STREX-deleted BK_Ca channels. Representative single channel current traces of the wild-type (A) and STREX-deleted (B) BK_Ca channels in the absence and presence of intracellularly applied Ter A. The membrane potential of the patch is +20 mV and [Ca²⁺]_i is 10 μM. Arrows indicate the closed state of the channels. (C) Summary of the effect of Ter A on the mean Po of the wild-type and STREX-deleted BK_Ca channel. **p < 0.005 compared to the control.