Figure 6.

Effect of methyl p-hydroxybenzoate on the open probability of single channels incorporated into lipid bilayers. TC vesicles were fused with lipid bilayers and single channel currents and amplitude histograms were measured as described in the Methods section. Single channel activity, recorded at 0 mV holding potential, exhibited an open level having a conductance of 75 pS and an open probability (Po value) of 0.221 in the controls (top trace) and 0.457 in the presence of 5 mM methyl p-hydroxybenzoate (middle trace). The subsequent addition of 10 μM ruthenium red fully inhibited the current fluctuations (bottom trace). The charge carrier was Na⁺ in a gradient concentration in the trans/cis compartment of 50/250 mM NaCl; c=closed channel, o=open channel.